Development of the female reproductive system. Development of the male reproductive organs

GENITAL ORGANS

The reproductive organs, or genitalia, provide for the development and excretion of germ cells, fertilization, and in mammals, also protection and nutrition of the embryo in the mother's body. The male and female genital organs are different in structure, but there is homology between them, due to the commonality of their embryonic rudiments. According to the functional purpose, three sections are distinguished in the male and female genital organs: the gonads, the genital ducts and the copulatory organs. The sex glands, along with the sex cells, produce hormones, that is, they have internal secretion. Male sex hormones - androgens and female sex hormones - estrogens affect the metabolism and growth of the whole organism, the development of the genital organs and secondary sexual characteristics largely depend on them. The endocrine function of the gonads is regulated by the anterior pituitary gland, which, in turn, is under the control of the nerve centers of the diencephalon.

In anatomy, it is customary to divide the genital organs into internal and external. The internal male genital organs are represented by the testicle and its appendage, the spermatic cord with the vas deferens, the seminal vesicles, the prostate gland and the bulbourethral glands. The external genital organs include the scrotum and the penis with the urethra. The internal female reproductive organs are the ovaries, fallopian tubes, uterus and vagina. The external female genital organs make up the female genital area.

Development of the sex organs

The sex organs develop from the mesoderm. A feature of their embryonic development is the presence of an indifferent stage, when the male and female genital organs are morphologically indistinguishable. Differentiation of male and female genitalia occurs at a later stage. Sex glands, genital ducts and external genitalia are formed from different but interconnected rudiments.

sex glands, gonads, are laid on the 3rd-4th weeks of development of the embryo in the form of a ridge-shaped compaction of the mesodermal epithelium of the secondary body cavity medially from the primary kidneys. The mesonephros and the indifferent gonad on the right and left sides of the mesentery of the intestine form the urogenital folds. The mesonephric duct stretches along the outer side of the roller, and on the medial side there is a thickening of the mesodermal epithelium, called the germinal, which is the anlage of the gonad. Among the epithelial cells of the anlage of the gonad are the primary germ cells. In a 4 mm embryo, approximately 1400 of these cells are found.

The mesonephric ducts and those laid next to them participate in the development of the genital ducts. paramesonephric(mullerian) ducts. The latter appear on the 5-6th week of the embryonic period, in their caudal part they connect with the mesonephric ducts.

Subsequently, the right and left urogenital ridges turn along their axis by 180° and fuse with each other with their outer edges from the bottom up. The paramesonephric ducts of the right and left sides approach each other, and if at first they were located laterally from the urogenital ridges, now they occupy a medial position. In the future, they fuse starting from the place where they came into contact and opened into the anterior cloaca or urogenital sinus.

On the 7-8th week of intrauterine life, sexual differentiation of the gonad occurs, and it begins to develop either as a testicle or as an ovary. If testicles develop, then strands of epithelial seminal cells are formed in the anlage of the sex gland on the 7th week. These strands take up a radial position, heading towards the place where the gonad connects with the body wall, and where a kind of mesentery is formed. In the future, the seed strands are bent. grow, divide into 3-4 new strands, spermatogonia develop in them, that is, cells that give rise to spermatozoa. After birth, gaps appear in the seminal cords, and they turn into seminiferous tubules, the structure of which is finally determined at puberty. At the mesentery of the testicle, the seminal cords are connected to each other into the network of the testis, and it, in turn, with some of the preserved urinary tubules of the primary kidney, which turn into the efferent tubules of the testicle. They open into the mesonephric duct, which becomes here the duct of the epididymis, further the vas deferens, and even further the vas deferens. The lower ends of the vas deferens expand in the form of ampoules. Later, from the 13th week of intrauterine life, seminal vesicles protrude from their walls. Thus, the development of the male gonad is characterized by the formation of seminal cords, which turn into seminiferous tubules and join with the urinary tubules of the primary kidney.

If an ovary develops, then the indifferent sex gland is divided, as a rule, into two layers. The outer layer is called the primary cortex, and the inner layer is called the primary medulla of the ovary. Primary germ cells are first located in the primary medulla of the ovary. Subsequently, the eggs move closer to the surface of the ovary, where they multiply intensified with the participation of cells growing from the surface from the layer of the germinal epithelium. This is how the secondary cortical substance of the ovary is formed. In the center of the ovary, in place of the disappearing primary eggs, connective tissue develops and the secondary ovarian medulla is formed, which is also first connected to a network of epithelial cells growing into the mesentery of the ovary. In the future, these cells undergo reverse development, as well as the adjacent urinary tubules of the primary kidney.

In the development of the ovary, the mesonephros is not as important as in the development of the testis. With the formation of the ovary, the mesonephric duct undergoes reverse development, while with the formation of the male sex gland, the paramesonephric ducts.

Several rudimentary formations are associated with the testicle and its appendage. testicle pendant, appendix testis, is a remnant of the paramesonephric duct. appendix of the epididymis, appendix epididymidis, is a rudiment of the duct of the primary kidney. deviating grooves, ductuli aberrantes, and the epididymis of the testicle, paradidymis, are formed from the collecting ducts of the primary kidney.

With the development of the ovary, the urinary tubules of the primary kidney do not connect to the ovary and undergo reverse development. However, some of them remain between the ovary and the fallopian tube in the form of 10-20 transverse ducts lying in the broad ligament of the uterus and connected by a longitudinal duct. It's an ovarian appendage epoophoron. Somewhat closer to the uterus, between the sheets of the broad ligament, an accumulation of convoluted epithelial tubules may appear, which is called the periovary, paraophoron, or an appendage of the epididymis. Vesicular pendants (hydatids) of the ovary are vesicles suspended on a stalk near the ovarian epididymis.

The mesonephric duct undergoes reverse development for most of its length, except for the place where it participates in the formation of the ovarian epididymis. However, sometimes the mesonephric duct persists for a longer distance. In about 25% of women, an epithelial cord stretches near the uterus and vagina - a rudiment of the mesonephric duct, called the Gartner duct. All these organs have no physiological significance, however, they easily undergo pathological changes and can give rise to tumors, in particular, those having the structure of fluid-filled blisters - the so-called cysts of the wide uterine ligament.

In men, the paramesonephric ducts are lost, except for the upper portions, which remain in the form of testicular appendages fused with the testis. The appendage of the epididymis is the remnant of the mesonephric duct, and the appendage of the testicle (or testis hydatid) is the remnant of the paramesonephric duct.

In women, the paramesonephric ducts give rise to the fallopian tubes, uterus, and vagina. Starting from the place of their confluence with the urogenital sinus, these ducts fuse with each other. From the part where they have grown together, the vagina and uterus develop, and the unfused parts give rise to the fallopian tubes. Initially, the paramesonephric ducts open into the urogenital sinus, which is a fairly long canal that resembles the male urethra.

Secondarily, during the development of the female fetus, the urogenital sinus lags behind in growth and is significantly shortened, so the vagina opens near the surface of the body into that part of the urogenital sinus, which turns into the vestibule of the vagina. In a ten-week-old female fetus, the uterus and vagina are not yet separated from each other, and the vagina opens deep into the pelvic part of the urogenital sinus. In a five-month-old fetus, the paramesonephric ducts, in the part where they have grown together, already represent the uterus and vagina. There are arches in the vagina, and it opens into the genital gap, that is, into the urogenital sinus.

An important process in the development of the internal genital organs is the lowering of the gonads. Descent of the testicles performed with the help of a special link - testicular conductor, gubernaculum testis, which is formed from the inguinal ligament of the primary kidney. This ligament is attached to the lower pole of the testicle, goes to the anterior abdominal wall and, passing through it, ends in the scrotum. With the reduction of the primary kidney, the testicle occupies an increasingly lower position on the posterior abdominal wall and shifts to the pelvic region at the 3rd month. At this time, at the lower end of the gland in front of the guide ligament, vaginal process of the peritoneum, which pushes the muscle layers of the anterior wall of the abdomen and also passes into the scrotum. The area in the circumference of the vaginal process and the guiding ligament of the testis represents the inguinal canal. At the 5th month of intrauterine life, the testicle approaches the deep inguinal ring, and at the 7th month it passes through the inguinal canal behind the vaginal process and wraps the peritoneum around itself, which forms the vaginal membrane of the testicle. At the end of the 8th month, the testicles are usually already in the scrotum, but often their descent is completed after birth. Together with the testicle, the reducing primary kidney moves into the scrotum, which forms the epididymis, and the mesonephric duct becomes the vas deferens.

Between the skin of the scrotum and the peritoneum lining it from the inside, there are several muscular and fascial layers, which represent the continuation of the layers of the anterior wall of the abdomen and form the shells of the testis. The vas deferens and the accompanying vessels and nerves, together with the sheaths covering them, form the spermatic cord. By the end of the intrauterine period, the upper part of the vaginal process of the peritoneum overgrows, and the serous cavity of the testicle is separated from the peritoneal cavity. In cases where obliteration of the vaginal process does not occur and communication with the peritoneal cavity is maintained, a congenital inguinal hernia is formed.

The biological significance of testicular descent is due to the fact that spermatogenesis occurs at a lower temperature than the temperature in the body cavity. In the scrotum, the temperature is 2.5-4° lower than in the abdominal cavity. The scrotum is a kind of thermostat for the testicles. In some animals, such as rabbits, the testicles descend into the scrotum during sexual activity, but when they rise into the abdominal cavity, spermatogenesis in them fades.

The descent of the ovaries is at first similar to the descent of the testicles. From the lower end of the ovary comes a guide ligament, similar to that of the testis. The ovaries, together with the paramesonephric ducts, are displaced into the pelvic cavity. The folds of the peritoneum covering them are transformed into broad ligaments of the uterus. The guiding ligament of the ovary forms its own ligament and the round ligament of the uterus. The latter, like the guiding ligament of the testis, passes through the inguinal canal and ends in the pubic region.

The external genital organs are also initially laid in an indifferent state. In connection with the transformation of the cloacal membrane, in place of its anterior part, a genital tubercle is formed along the midline. Behind it is a longitudinal urogenital groove leading to the urogenital sinus, bounded by two urogenital folds. On both sides of it appear sexual ridges, or genital elevations.

From the 8th week of development and during the 3rd month of intrauterine life, if a male fetus develops, the genital tubercle grows strongly, lengthens and turns into a male penis. The urogenital folds limit the urethral groove, and then approach each other, connect and close the outer part of the urogenital sinus into the spongy part of the urethra. The genital ridges approach each other, move caudally and fuse into the scrotum, where the testicles move at the end of fetal life.

If the development of the fetus follows the female path, then the changes in the external genital organs are much less profound. The genital tubercle becomes the clitoris, the urogenital folds turn into the labia minora, the urogenital sinus between them does not close, but, on the contrary, becomes wider and remains open in the form of a gap in the vestibule of the vagina. In the same way, the genital ridges do not grow together, but turn into large labia.

Plays a role in the formation of the external genitalia definitive urogenital sinus, due to which all parts of the male urethra are formed below the confluence of the ejaculatory ducts into it, and in the female body - the final part of the urethra and the vestibule of the vagina. In the place where the urogenital sinus connects with the paramesonephric ducts, there is a fold from which the hymen is formed. Glands are laid in the urogenital sinus and urethra in embryos, from which the prostate and bulbourethral glands are formed in the male body, in the female body - large and small vestibular glands, as well as paraurethral ducts.

The differentiation of the internal and external genital organs is under the control of genetic and hormonal factors. The chromosomal conditionality of the development of male or female genital organs is decisive, however, the female XX karyotype does not in all cases determine development to the female side, and the male XY karyotype to the male side. It is still not known what processes determine the development of the sex gland in the direction of the testicle or ovary. The transformations of the mesonephric and paramesonephric ducts are under the control of substances produced by the gonads. It is believed that there is a neutral type of genital ducts, which is close to the female type, and that development in the male side occurs under the influence of androgens. If this influence is absent, internal genital organs of the female type are formed. The leading role in the differentiation of the external genital organs is played by androgens; their presence is necessary for the development of male reproductive organs. In the absence of androgens, the external genitalia are formed according to the female type.

Both genetic and hormonal factors can cause deviations from the normal development of the sex organs. Chromosomal anomalies, as well as changes in the hormonal balance in the body of the embryo and fetus, cause developmental disorders, which we will focus on in the further presentation of the material.

Male reproductive organs

Testicle is a complex tubular gland, the parenchyma of which is made up of convoluted and straight seminiferous tubules and the interstitium surrounding them. Spermatogenesis occurs in the convoluted tubules. Through the direct and further through the efferent tubules, the sperm enter the duct of the epididymis. The testicle is also an endocrine gland that synthesizes and releases male sex hormones.

In a newborn baby, the testicles are relatively large. The length of the testicle is 10.5 mm, weight - 0.3 g. During the first year, the testicles grow rapidly, the mass of the organ increases to 1 g, then growth slows down until puberty, when there is a rapid increase in the gonad. The length of the testicle is at the age of 5 years 15 mm, at 15 years old - 20 mm, at 18 years old - 40 mm, in an adult - 50 mm. The mass of the testicle at the age of 14 is only 2 g, and at the age of 15-16 it is already 8 g. By the age of 20, the mass of the testicle reaches 20 g and does not change until the age of 50. After 50 years, atrophic changes occur in the parenchyma of the testicles, and their function decreases. In old age, the mass of the testis decreases to 11-12 g. The seminiferous tubules in newborns and in childhood do not have a pronounced lumen, at 14-16 years old, due to the onset of spermatogenesis, the diameter of the tubules increases, and a lumen forms in them. The length of one seminiferous tubule is 70-100 cm, and the total length of the tubules of one testicle reaches 250-400 m. Each lobule of the testicle contains 1-2 convoluted seminiferous tubules surrounded by 4 capillaries.

epididymis plays the role of sperm storage. In newborns, it is relatively large, its length is 20 mm. In the first 10 years, the appendage almost does not grow; during puberty, its size increases significantly. The mass of the epididymis in an adult is 4 g. The diameter of the duct of the epididymis in the middle part is 0.5 mm, the total length reaches 6 meters.

The shape and size of the testicles vary individually. Their characteristic feature is asymmetry. The left testicle is located, as a rule, lower than the right one, but in some cases the right testicle occupies a lower position. This is observed, for example, with the reverse position of the viscera. In terms of mass, the left testicle somewhat predominates over the right.

spermatic cord extends from the internal opening of the inguinal canal to the upper end of the testicle. It distinguishes the inguinal and scrotal parts. The length of the cord depends on the position of the testicle and is 15-20 cm. The composition of the spermatic cord includes: 1) the vas deferens; 2) artery of the vas deferens; 3) testicular artery; 4) testicular vein, which originates from the pampiniform plexus; 5) nerve plexuses of the vas deferens and testis; 6) lymphatic vessels; 7) remnants of the vaginal process of the peritoneum; 8) smooth muscle tissue; 9) loose connective tissue with a large number of elastic fibers, devoid of adipose tissue; 10) a rudimentary formation "appendage appendage", located in the lowest part of the funiculus.

The spermatic cord has a system of membranes, which includes: 1) external spermatic fascia; 2) fascia of the muscle that lifts the testicle (begins only below the external opening of the inguinal canal); 3) the muscle that lifts the testicle; 4) internal seminal fascia.

vas deferens represents a channel for conducting the seed, which has a relatively narrow lumen and thick walls, formed mainly due to the muscular membrane. The end of the vas deferens connects with the excretory duct of the seminal vesicle, forming the ejaculatory duct, which opens with a slit-like opening on the seminal tubercle in the prostatic urethra. The ejaculatory duct is surrounded by cavernous tissue and muscle tissue of the prostate gland, due to which its lumen is closed. During sexual intercourse, the seed flows from the epididymis into the vas deferens. In its final section, the secret of the seminal vesicle is secreted, which represents a nutrient and protective environment for spermatozoa. During ejaculation, there is a simultaneous general contraction of the muscles of the vas deferens, and seminal fluid is pushed through the vas deferens into the urethra. The volume of erupted seminal fluid is 2-6 ml, on average 3.5 ml.

Prostate was named for its position in front of the bladder during an operative approach to it from the side of the perineum. The organ has a glandular-muscular structure. Three groups of glands are distinguished in the gland: 1) periurethral, located in the circumference of the urethra; 2) internal; 3) external, occupying the periphery of the body. The ducts of the glands in the amount of 16-32 open into the prostatic part of the urethra. The secret of the prostate gland has an alkaline reaction, thanks to which it stimulates the movement of spermatozoa. Smooth muscle tissue makes up about 1/4 of the mass of the organ. Muscles contribute to squeezing out the secret from the gland, and during ejaculation they are involved in closing the initial part of the urethra, preventing the seed from being thrown into the bladder.

In newborns, the prostate gland, like the seminal vesicles, is located higher than in adults. The shape of the gland is spherical, the lobes are not differentiated, the glandular tissue is poorly developed. In the first ten years of life, the mass of the prostate increases by half, and between 10 and 15 years more than doubles. During puberty, the gland acquires its characteristic chestnut shape, it reaches its full development by the age of 21-25. Its mass in an adult is 16 g. In old age, gland hyperplasia often occurs. At the same time, the periurethral and internal glands increase, and the outer part of the gland undergoes atrophy. Hyperplasia of the gland leads to squeezing of the urethra, and it is necessary to resort to its prompt removal.

male urethra in adults it has a length of 20-25 cm and is divided into prostatic (3-4 cm), membranous (1-2 cm, on average 1.5 cm) and spongy (15-17 cm) parts. In newborns, the length of the canal is 5-6 cm, of which about 1/3 falls on the prostatic and membranous parts, while in adults only 1/6 of its length. This feature is due to the fact that in newborns the bottom of the bladder is high, and the penis is small. The diameter of the lumen of the urethra is not the same throughout. There are 3 narrowings of the canal: 1) in the region of the internal opening, 2) in the membranous part, 3) in the region of the external opening; and 3 extensions: 1) in the prostate, 2) in the region of the bulb of the penis, 3) in the region of the glans penis (navicular fossa). The narrowed and dilated sections of the urethra in children and adults correspond to each other. The bends and narrowing of the canal should be taken into account when introducing a catheter or cystoscope into it.

Penis is the male copulatory organ. It consists of paired cavernous bodies and an unpaired spongy body, in which the urethra passes. The structure of the cavernous and spongy bodies is characterized by the presence in their tissue of cells into which the helical arteries open. The vessels of the penis are equipped with devices that regulate the inflow and outflow of blood. With sexual arousal, an erection of the cavernous bodies occurs, their cells fill with blood, and the protein membrane of the cavernous bodies tenses. Cavernous bodies increase and become densely elastic. The study of blood flow in the vessels of the penis during its erection shows that an erection occurs with an increase in arterial inflow and effective shunting of blood flow from the arteries to the cells of the cavernous bodies. Obstruction of venous outflow does not play a significant role in maintaining an erection.

In newborns, the length of the penis is 2-2.5 cm, the foreskin almost completely covers the head of the organ and partially fuses with it. The spongy body is more developed than the cavernous bodies. Until the age of 4, the penis almost does not grow, at the age of 7, its length is 4.5 cm. In adolescence, the penis grows mainly in length, and with the onset of puberty, its thickness rapidly increases. In adults, the length of the penis averages 8-10 cm with individual variations from 6 to 14 cm. The diameter of the organ is 2.5 cm. When erect, the length of the penis reaches 20 cm, the diameter is 3-4 cm.

Female reproductive organs

Ovary, like the testicles, is an organ for the formation of germ cells and the production of sex hormones; functionally, the ovary plays a leading role in the female reproductive system.

In a newborn girl, the ovaries, along with the fallopian tubes, are still above the entrance to the small pelvis, they can be shifted forward, to the deep inguinal ring or back, to the promontory. The shape of the ovaries is cylindrical, the mass is 0.2 g. The ovaries descend into the small pelvis in the first months after birth. Their mass reaches 0.6 g by the end of the first year, by 4-7 years - 2 g. Before the onset of puberty, the ovaries grow slowly, at the age of 7-14 years they weigh 3.3 g. During puberty, the mass of the ovaries increases to 6 g, and in 20-30 years reaches the final value, which varies from 7 to 14 g (average 10.7 g). In old age, significant atrophy of the organ occurs.

The ovaries of an adult woman are located on the side wall of the pelvis in the middle between the plane of its upper aperture and a plane parallel to it, passing through the lower edge of the pubic symphysis. In a nulliparous woman, the length of the ovary is located almost vertically. In a woman giving birth, due to overstretching of the ligamentous apparatus of the uterus and ligaments of the ovary, the latter is in a semi-horizontal position. The ovaries lie in the cavity of the peritoneum, they have a protein membrane and are covered on the outside with a surface epithelium. The ovary is divided into cortex and medulla. The boundary between them is expressed indistinctly. The medulla consists of connective tissue with vessels and nerves branching in it (vascular zone). The cortex contains 2 million primary follicles in newborns in both ovaries, in which germinal eggs are located. After birth, atresia of the follicles occurs, and upon reaching puberty, 155,000 of them remain in the ovaries. When the egg matures, the primary follicle turns into a secondary, and then a tertiary vesicular follicle (graafian vesicle). Next, ovulation occurs, that is, the rupture of the follicle and the release of the egg from the ovary. In place of the tertiary follicle, a corpus luteum is formed.

During the reproductive period, which lasts for a woman from the time of the onset of the first menstruation to 40-50 years, no more than 400-500 eggs have time to mature. The rest die, and the follicles in which they are located undergo atresia. Cyclical changes in the ovary associated with ovulation and the formation of the corpus luteum are under the control of pituitary gonadotropic hormones and, in turn, are accompanied by the production of hormones that cause changes in the uterus associated with the menstrual cycle and pregnancy.

Oviduct represents the channel through which the egg, released from the ovary during ovulation, is carried to the uterus. It has been established that the fimbriae of the tube move to the site of rupture of the follicle, and the ovarian fimbria covers this area. The funnel of the pipe at the same time rhythmically narrows and expands, making suction movements.

The length of the fallopian tube in adults is 7-14 cm, on average 11 cm, and the diameter of the lumen is 2-4 mm. The passage of the egg through the tube to the uterus occurs within 3-4 days. Fertilization occurs, apparently, in the ampoule of the tube, since the egg retains the ability to fertilize for no more than 12 hours. For comparison, it should be noted that the passage of sperm from the vagina to the end of the fallopian tube takes about 3 hours, and their ability to fertilize varies from 1.5 to 72 hours. In the promotion of the egg to the uterus, the features of the mucous and muscular membranes of the tube play a role. Mucosal folds, surrounding the egg from all sides, create favorable conditions for metabolism and soften the pressure on it from the muscles. The muscles of the fallopian tube provide two types of movements: corkscrew, towards the ovary during ovulation, and peristaltic, directed towards the uterus.

Uterus occupies an anatomically central position in the female reproductive system, however, its development and functional state depend on the hormonal function of the ovaries. The uterus provides the perception of a fertilized egg, nutrition and protection of the developing embryo and excretion of a mature fetus from the body. The first two functions are associated with the mucous membrane, and the last - with the muscular membrane of the uterus.

Parts of the uterus, as well as its ligamentous apparatus, differentiate on the 3rd month of intrauterine development. In the fetuses of the last month and in newborns, the uterus has a cylindrical shape, its length is 27-36 mm, and its weight is 2 g. The predominance of the neck over the body in a ratio of 2: 1 is characteristic. The fundus of the uterus is located above the upper pelvic inlet, and the opening of the uterus is located above the lower edge of the pubic symphysis. Due to the weak development of the ligamentous apparatus, the uterus is not sufficiently fixed and is easily displaced. In 3/5 cases it is deviated to the right and in 2/5 to the left from the median plane.

After birth, during the first month, the uterus not only does not grow, but even decreases in size. Up to 10 years, the growth of the uterus is slow, mainly due to its body. In childhood, the body and cervix are approximately the same length. In the third five years, the growth of the uterus accelerates, and the body again grows faster than the neck, and with the onset of puberty begins to prevail over the latter. The mass of the uterus at 11-15 years old is 6-7 g, at 16-20 years old it exceeds 20 g. The mass of the uterus in nulliparous women varies from 40 to 50 g, and in those who have given birth - 80-100 g. 7-8 cm, for a woman giving birth - 8-9.5 cm. Of these, 2/3 falls on the body and 1/3 is the cervix. The volume of the uterine cavity is from 4 to 6 cm 3 .

The position of the uterus depends on the position of the body, the filling of neighboring organs, the state of the ligamentous apparatus. The position of the uterus changes dramatically during pregnancy. The uterus is not always located strictly symmetrically. tilting the uterus back retroversion, and especially the backward bend, retroflexio may be accompanied by painful symptoms.

Vagina represents a connective tissue-muscular tube, is a copulatory organ and a channel for removing the fetus during childbirth. The length of the vagina in a newborn girl is 25-35 mm, at 10 years old it reaches 5 cm. In adults, the length of the anterior wall of the vagina is 5.5-7.5 cm, the length of the posterior wall is 7-9 cm, the width of the lumen is 3 cm, the wall thickness is 2 mm . At birth, the anterior wall of the vagina borders the urethra, later in its upper part it comes into contact with the descending bladder. The back wall borders in all age periods with the rectum.

The upper part of the vagina forms a vault around the cervix protruding into it. With sexual arousal, the vaginal mucosa secretes a liquid secret, the vagina lengthens, its upper part expands, forming a seed receptacle. During intercourse in the lower part of the vagina, the walls swell, depending on the filling of the venous plexus located here with blood. A cuff is formed, covering the penis (orgastic platform).

External female genital organs have the following age characteristics. In newborns, the pubis is a triangular elevation, delimited by a furrow from the hypogastrium. The labia majora are strongly developed in their posterior part and do not completely cover the labia minora, which protrude from the genital slit. The vestibule of the vagina is limited only in the anterior 2/3 by the labia minora, behind it is limited by the large lips. The clitoris is relatively long, its foreskin and frenulum are well developed. The external opening of the urethra lies deep and is difficult to detect. The hymen is thick, built of dense tissue. After birth, the content of adipose tissue in the labia majora increases, and they close the genital gap more tightly. In the first 3-4 years, glands develop in the labia minora and the vestibule of the vagina. The growth of the genital organs most intensively occurs during puberty. During this period, pubic hair appears.

Individual differences in the external female genital organs are expressed in the degree of development of large and small lips, the size of the clitoris, the nature of pubic hair and labia majora. Depending on the predominant localization of hair, there are pubic, labial and combined types of hair growth.

The shape and structure of the hymen are subject to great variability. Its variants are of interest mainly for forensic medicine. The most common forms are the lunate and annular hymen. There is a hymen with two or more holes, a fringed edge. In rare cases, the hymen is devoid of a hole, and it has to be artificially perforated. During the first sexual intercourse, the hymen usually breaks (defloration) and forms carunculae hymenales. During childbirth, the hymen is almost completely destroyed.

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Violation of the formation of the genital organs includes a whole group of diseases of a congenital nature, which manifest themselves in various developmental disorders on the part of the reproductive system. In this article, we will look at what causes disorders, find out what are the signs of disorders and how to treat these diseases.

The reasons for the violation of the formation of a normal sex may be the following:

Anomalies of the genetic apparatus. In this case, the nature of the disorders directly depends on the affected gene;
Chromosomal diseases, the most common of which are Turner-Shereshevsky's disease, Klinefelter's disease, etc.

Violation of sex formation should be detected as early as possible, otherwise it will subsequently lead to the formation of a more severe pathology in the form of false male, false female or true hermaphroditism.

In male fetuses, sexual dysfunction most often due to a violation of the formation of the male gonads - the testicles and, as a result, a violation of the release of male sex hormones, in particular testosterone. Sometimes the secretion of hormones remains at a normal level, while the tissues of the body simply stop responding to them. All these changes can lead to false male hermaphroditism.

In female fetuses, a violation of the formation of sex occurs either as a result of excessive release of male sex hormones in the body of the fetus (for example, with adrenal insufficiency), or when these hormones are in excess in the mother's body and act on the child's genitals. All of the above leads to the development of false female hermaphroditism.

The reasons for the development of male and female true hermaphroditism are still not fully understood. Changes in the genetic apparatus, which theoretically can lead to the development of pathology, are detected only in a fifth of all patients.

The reproductive organs of the fetus are formed around the 8-15th week of pregnancy. It has been proven that for the normal formation of male genital organs, it is necessary to have a sufficient level of male sex hormones in the blood of the fetus. If they are not enough, then the genitals do not acquire the proper male signs of development and become similar to female ones.

The formation of female genital organs occurs without the participation of hormones at all. If, however, excess male sex hormones enter the fetus in any way, then the genitals develop incorrectly, according to the male type.

Signs of the disease

Since the concept of the incorrect formation of the genital organs is quite broad, there are a huge variety of various forms of diseases in this group. However, they all have some common features. All violations are usually divided into two large groups: with the presence of hermaphroditism and without it. In case of violations without hermaphroditism, the genitals of the child at birth and later are arranged at first glance correctly and look like female or male. However, in the future, during puberty, signs of insufficiency of the gonads begin to appear. Growth retardation begins, a slowdown in the development of the genital organs, and infertility develops in the future. During the neonatal period, the presence of pathology can be suspected, since these children often have multiple malformations of various organs. The following are hereditary diseases, most often accompanied by a violation of the development of the genital organs in a child.

Turner-Shereshevsky syndrome

The reason is the absence of one of the X chromosomes in the cells of the body. As a result, there is a violation of the development of the ovaries.

The disease can be suspected even in infancy. Immediately after birth, you can see swelling located on the hands and feet of the child, which continues until the age of 1-3 months. There is also swelling on the neck, but subsequently it does not disappear, but turns into a fold that remains on the skin. The child's body weight is below normal, growth also lags behind, muscles are weak. In some patients, defects of various internal organs are subsequently detected. The genital organs are reduced in size and underdeveloped, although they always have the appearance of a woman. The clitoris is enlarged. The most significant lag of patients in growth and development is observed during puberty. Underdevelopment of the genital organs is pronounced. The uterus and ovaries are very small and incapable of performing a reproductive function. Sometimes the ovaries may be absent altogether. The mammary glands in these girls do not grow. There is no secondary hair growth in the armpits and on the pubis. Most of the time menstruation never comes. With Turner-Shereshevsky syndrome, the severity of abnormal sexual development may be different. In some patients, it is even possible to develop male-type genital organs.

In this case, when examining the chromosome set, a male Y-chromosome is found in some of the cells of such patients. The presence of the disease in all cases is confirmed by examining the chromosome set of patients. Only one X chromosome is found in the genome, which indicates the presence of pathology. The internal genital organs are examined using ultrasound methods. A very informative study of sex hormones in the blood. In parallel, malformations of other organs are detected, of which the kidneys and heart most often suffer.

Treatment of Turner-Sherevevsky syndrome consists of several directions.

Treatment of malformations. Some of them are corrected surgically, others are treated with medication. An operation is required to remove and further study the primordia of the ovaries.
A very important point is the correction of low growth. Currently, for this purpose, the introduction of growth hormone, steroid hormones to patients is used.
Treatment with preparations of female sex hormones in order to eliminate the delay in sexual development and prevent complications associated with it.
Modern technologies allow such manipulations as artificial insemination and the introduction of a diseased donor egg with the subsequent possibility of carrying a pregnancy. This is a very important event, as it allows for the maximum rehabilitation of the patient in society.

Swyer syndrome

This term is understood as a violation of sexual development in boys in the presence of a normal set of male sex chromosomes in their cells. In this case, the genital organs develop according to the female type. The disease itself can be caused by various subtle breakdowns in the genetic apparatus. Most often, in the presence of X- and Y-chromosomes, their abnormal structure, doubling or loss of any part of them is revealed.

Outwardly, the patient is a completely normally formed woman. Its growth has average values or is slightly increased. Mental development is normal. The internal and external genitalia are female. The clitoris is somewhat enlarged. The ovaries and testicles are absent, instead of them there are small strands. It is very difficult to diagnose the disease in childhood. It is easier to suspect it during puberty, when it lingers in a girl. The rudiments of the sex glands subsequently very easily degenerate into tumors.

Treatment of the disease. Immediately after the detection of pathology, the rudiments of the sex glands must be removed surgically, as they can degenerate into a tumor. The patient is recognized as a woman, treated with female sex hormones.

Forecast quite favorable, if there are no complications and competent treatment is carried out.

Klinefelter syndrome

The disease occurs in children whose genotype contains one Y and two or more X chromosomes. An excess X chromosome is responsible for the development of a number of disorders in the body, including the underdevelopment of the male gonads. In adult patients, there are practically no spermatozoa in the seminal fluid, they are infertile. The genitals, however, have the appearance of a man. Only in some cases, sexual development in adolescence can be delayed, most often it is not disturbed at all.

In infancy, the manifestations of the disease are practically absent. It is impossible to identify the disease before the onset of sexual development, since it manifests itself very uncharacteristically: mental development lags behind a little, children are restless for no reason, they behave either too cheerfully or very aggressively, they study worse at school than their peers. Such children are stunted, they are thin, with long legs. Body weight is low. On the part of the genital organs, there is a decrease in the testicles, penis, the testicles may not be in the scrotum, but in the abdominal cavity. Sometimes the urethra is split from below. Puberty starts late. Hair growth on the body occurs according to the female pattern. Some patients develop mammary glands. It is very characteristic that during puberty, the testicles almost do not increase in patients at all. Infertility is also a characteristic feature. The ability to perform sexual intercourse is preserved.

These are the signs of the disease if the patient has only one extra X chromosome. If their number is greater, then the picture is even brighter. All of the above symptoms are much more pronounced.

The study of sex chromosomes, the content of female and male sex hormones in the blood helps in the diagnosis of the disease.

Treatment , as a rule, is not appointed before the age of 13-14. The reason for the appointment of therapy is a violation of sexual development and laboratory signs of a decrease in the function of the gonads. Long-acting male sex hormone therapy is used. In the presence of mammary glands, they are removed surgically.

Hermaphroditism

This is such a violation of the development of the genital organs, when instead of the normal genitalia inherent in this sex, the genitalia of both one's own and the opposite sex develop. The disease also has several different forms, but they practically do not differ in anything, except for the degree of severity of the existing malformation.

In girls, only five degrees of developmental disorders are distinguished. The first is characterized by the fact that the genitals are only slightly similar to the male, and the fifth proceeds with the development of typical male genitalia. In boys, the spectrum of severity of the defect is approximately the same. Other disorders may include an extremely small penis, splitting of the penis and scrotum, one or both of the testicles in the abdomen, the testicles may be underdeveloped or absent, but rarely remain completely normal.

With the child's further achievement of the age of puberty, it as such is absent. If it nevertheless occurs, then it proceeds incorrectly: it is premature, female signs develop in boys, and vice versa, signs of both sexes can develop simultaneously. Variants are described when menstruation was observed and at the same time spermatozoa were actively excreted. Below are the main diseases accompanied by the development of hermaphroditism.

Mixed violation of the development of the rudiments of the genital organs

The causes are often various chromosomal diseases. The structure of the genital organs in these children cannot be described unambiguously. In the clinic, there are options from almost normal female to almost normal male genitalia. The sex glands are arranged in a very peculiar way: on the one hand there is an almost normal testicle, and on the other, an almost normal ovary. Accordingly, the internal genital organs are arranged: on the one hand, half of the uterus with the fallopian tube, and on the other, the vas deferens. Since the disease is by its nature close to Shereshevsky-Turner disease, its characteristic signs are often revealed. When entering the period of sexual development, it proceeds slowly, the genitals are reduced in size. Sometimes male secondary sexual characteristics develop. When deciding on the gender of a child, they are guided by the degree of severity of male or female sexual characteristics. Most often, the newborn is assigned the female gender.

Violation of the development of the genital organs with signs of false male hermaphroditism. The disease also has a genetic nature and is caused by an excess of certain genes. In this case, the testicles on both sides are severely underdeveloped. The internal genital organs are female (there is a uterus, fallopian tubes), and the external ones are male (penis, scrotum). Puberty in the corresponding period of life does not occur. In some cases, the disease is combined with many malformations of internal organs.

When choosing the sex of a child, they are guided by the degree of development of male sexual characteristics and the possibility of eliminating malformations of the genital organs with the help of surgery.

Sex gland regression syndrome

This includes a group of diseases, the common feature of which is the regression of the previously formed seminal glands. There are three degrees of underdevelopment of the testicles: the complete absence of the gonads, the deep underdevelopment of the testicles, and the absence of one or both testicles.

In the complete absence of the sex glands, the external genital organs are arranged according to the female type. The internal genital organs are underdeveloped, but have the appearance of a man. The disease can be combined with malformations of other organs, abnormal development of the child's face.

With a deep underdevelopment of the testicles, they are significantly reduced in size, are in the scrotum or do not fall completely and are located higher. It is clear that the function of such underdeveloped testicles will be significantly reduced. The external genital organs are formed either as female or as male, but the size of the penis is very sharply reduced. All internal genital organs are male.

The absence of testicles is always observed against the background of normally formed internal and external male genital organs.

With all the above forms of the disease, puberty occurs late, proceeds slowly, the function of the genital organs is sharply reduced. The sex of the child is recognized as male, he will adapt well in society in the future, provided that hormone therapy is carried out and gross violations are corrected surgically.

Violations of the formation of the male sex hormone - testosterone

In such patients, the testicles are not fully formed and are not lowered into the scrotum. All internal genital organs are male, and external - female. As a rule, not only the sex glands are affected, there is also an insufficient function of the adrenal glands. In the future, the child lags behind in growth and mental development. During puberty, signs of male sex appear, less often puberty does not occur at all. The child is assigned the male gender.

Syndrome of lack of sensitivity of body tissues to male sex hormones

The disease is hereditary. There are two forms of the disease - complete and incomplete. The differences are that with complete external genitalia - female, and with incomplete they have features of both female and male. The testicles do not fully descend into the scrotum, are located in the inguinal canals, their size is normal or enlarged.

Internal genital organs of the male type

Growth is high, mental development does not suffer. In this situation, the most appropriate is to give the child a female passport.

Violation of testosterone synthesis

As you know, testosterone is the main hormone produced by the male gonads. The external genital organs with its deficiency are formed incorrectly, and the degree of violation can be very different. The testicles are located in the abdominal cavity. Puberty never occurs. Since all other male sex hormones, except for testosterone, are produced in normal quantities, the sex of the child should be recognized as male.

Adrenogenital syndrome girls

It develops due to the influence of male sex hormones on a 12-week-old female fetus. At the same time, in a born child, the internal genital organs are always female. There is an almost normal uterus and its tubes, the vagina. The external genital organs become similar to male ones, and this can be expressed to varying degrees, depending on the degree of excess of male sex hormones. If adequate treatment is not started from an early age, then in the future puberty occurs very early and male sexual characteristics appear. Gender is most often recognized as female.

Violations of sexual development in the pathology of the adrenal glands

They develop in a child if during pregnancy the mother took drugs of male sex hormones, large doses of female sex hormones. The reasons may be in the pathology of the adrenal glands of the fetus itself. The external and internal genital organs are arranged according to the female type, but the external genitalia are arranged somewhat incorrectly. In the future, puberty proceeds rapidly, the bones of the skeleton ossify in accordance with age. The fetus is assigned a female gender. Special treatment of the given pathology is not required, it is only necessary to eliminate the irregular shape of the external genital organs with the help of an operation.

True hermaphroditism

As mentioned above, the true causes of this pathology remain unclear to date. At the same time, the same child has both male and female genital organs. At the onset of puberty, both male and female secondary sexual characteristics appear. When choosing the sex of a child, they are guided by which of the genital organs are more pronounced. Most often, gender is recognized as female.

Rehabilitation of patients with impaired development of the genital organs is a very topical issue at the present time. This is due, firstly, to an increase in the number of children with similar developmental defects, and secondly, to the fact that the presence of a defect in itself is in the future a deep mental trauma for a particular child. Rehabilitation activities begin with the choice of the sex of the newborn. This is determined by the nature of genetic disorders, the possibility of surgical correction of the existing defect. In this case, the further social adaptation of the child actually depends on the literacy of the doctor.

Forecast. In relation to life, always favorable. With regard to the preservation of sexual function and the possibility of having offspring, he is always very doubtful.

The biological maturity of the human body occurs during puberty, when the sexual instinct awakens. During the transitional period, the activity of the endocrine glands is activated, the genital organs develop. The period when puberty occurs, and its intensity, may be different and depend on the nature of nutrition, health status, climate, socio-economic and living conditions. An important role belongs to hereditary features.

Development of the female reproductive organs

The development of the female genital organs is characterized by uneven completion in different age periods until puberty occurs. In the womb, the girl's genitals grow unevenly, which is explained by the action of the mother's estrogenic substances, or, more precisely, placental hormones. Estrogen hormones continue to influence the state of the girl's genitals for some time after her birth, and its manifestations are the characteristic morphological and biochemical features of the girl's body. In addition, there are some striking functional manifestations, among which, for example, the discharge of blood and mucus from the genital slit in newborn girls, enlargement of the mammary glands and the release of colostrum. These phenomena are called the sexual crisis of newborns.

But placental hormones affect the girl for a short time. The content of estrogenic substances in the urine of newborn girls noticeably decreases within 5-6 days after birth, and therefore the genitals undergo reverse development, which is characterized by a slower course. In the future, the genitals of the girl can be characterized by "neutral" growth, i.e. free from the pronounced influence of sex hormones, when compared with other organs. In particular, the uterus reaches the size characteristic of the period of hormonal hypertrophy of newborns by about 10 years of age. More intensive growth of the genitals begins at 9-10 years of age.

Thus, development can be characterized as follows:

increased growth shortly before birth;
reverse development shortly after birth;
slow growth of the genitals in the first years of life;
enhanced by development in the prepubertal and, in particular, pubertal periods.

Development of the genital organs in boys

The genitals in boys begin to develop even when the fetus is in the womb, in the third month of pregnancy. First, the formation of the glans penis and its cavernous bodies. After that, there is an increase in the skin of the penis. At the same time as the formation of the penis and urethra, the formation of the scrotum occurs. The male gonads (testicles) descend into the scrotum at the 8th month of pregnancy. Intensively, the testicles begin to grow from the moment of birth and up to a year, their size increases on average by 3.7 times, and their weight - by 3.6 times. At the age of 10 to 15 years, there is an increase in the size of the testicles by 7.5 times, weight - by 9.5 times.

The prostate and seminal vesicles perform the function of additional glands of the reproductive apparatus. Until the moment when puberty sets in, the prostate is a muscular organ, the development of the glandular part of which occurs before, and the achievement of the definitive structure refers to 17 years.

Features of puberty

During puberty, the whole organism is restructured, the psyche of a teenager changes. The peculiarities of the period of puberty are its unevenness, the advance of some processes by others, the decrease in working capacity, the occurrence of neurotic reactions - irritability, tearfulness.

New relationships between the sexes begin to emerge, boys try to show their strength in front of girls, girls are characterized by an increase in interest in their appearance. Sometimes the first love experiences lead to the fact that teenagers begin to study worse, become withdrawn.

The external genital organs are laid in the same way in embryos of both sexes in the region of the cloacal membrane, which is the ventral wall of the cloaca. A spur-like protrusion of the coelom (urorectal fold) divides the cloaca into two sections: dorsal (anlage of the rectum) and ventral (more extensive primary urogenital sinus). With an embryo length of 15 mm, the urorectal fold reaches the cloacal membrane, divides it into anal and genitourinary parts, forming the primary perineum. From this point on, the development of the intestines and the genitourinary system occurs in isolation.

There is no consensus on the timing of laying the external genitalia.. According to some authors, this occurs on the 5th week with an embryo length of 13-15 mm; according to others - on the 6th; still others attribute their appearance to the 7th week of embryonic life. Differentiated, sex-appropriate development of the external genital organs begins at the end of the 3rd month of the embryonic period. In the male fetus, this process is carried out for a period of 9-10 weeks under the control of embryonic androgens. In female fetuses, feminization of the external genitalia is observed from the 17th to 18th week of pregnancy.

external genitalia of the examined embryos and fetuses (8-10 weeks of pregnancy), the sex of which was determined by the histological picture of the gonads, consist of labioscrotal folds and the genital tubercle.

The urethral groove runs on the dorsal surface of the genital tubercle. Its edges in the form of thin low plates close the primary urogenital opening of a slit-like form, which was formed after the opening of the urogenital membrane. The narrow laying of the primary perineum separates the urogenital fissure from the anus. The base of the genital tubercle covers the arcuate labioscrotal folds (genital folds). The fetuses of both sexes at this stage have an identical structure of the external genitalia, which we, like previous researchers, classify as neutral, indifferent.

In the second half of the prefetal period (11-13 weeks of pregnancy), the nature of the external genitalia in the female fetus remains unchanged. Only at the pudendal tubercle does the direction change slightly: from vertical it becomes dorsocaudal.

At the stage of 14-16 weeks, the ratio of the parts of the external genitalia remains the same. Increasing in size, they do not undergo morphological changes. The genital tubercle (clitoris), due to the significant predominance of longitudinal dimensions over transverse ones, looks especially large. While maintaining a dorsocaudal direction, it sharply protrudes from the underdeveloped labia majora, which remain narrow (1–2 mm) and flat, expressed only in the upper 2/3 of their length. The ratio of the length of the clitoris to its thickness is 3:5. Anogenital distance is 3 mm.

The period of 17 - 19 weeks is characterized by significant shaping processes that give the external genital organs of the fetus specifically female features. There is a rapid development of the labia majora. Passing from the front into the pubic tubercle, and from behind converging at an acute angle into the posterior commissure, they close the pudendal fissure. The clitoris, due to the increase in transverse dimensions, becomes relatively shorter, the small labia formed from the edges of the urethral fissure close over the clitoris in the form of a foreskin.

Along with morphological changes, there is a rapid growth of all components of the vulva, except for the clitoris.

At subsequent stages of intrauterine development, a uniform increase in the size of the external genitalia is observed, proportional to the overall growth of the fetus.

The length of the large shameful lips, as a rule, is equal to the length of the genital slit and reaches 35-36 mm by the time of the onset of childbirth. The older the fetus, the more elastic and fuller they close the genital gap.

Small shameful lips for a period of 17-18 weeks, they are thin skin folds up to 4 mm long (1/3 of the length of the labia majora). This ratio is maintained up to 23 weeks; then the growth rate of the small pudendal lips exceeds that of the large ones, and in a full-term fetus, the small lips are 2/3 of the length of the large ones. In an immature fetus, small shameful lips protrude from the gaping genital slit, and by the onset of urgent delivery, they are usually completely covered by large ones. There may be an unexpressed asymmetry in the size of the right and left lips, both large and small.

The clitoris undergoes interesting changes. With the growth of the fetus, it becomes wider, almost without increasing in length: by the 23-24th week, the ratio of its length to width is already less than 2, and in a full-term fetus it approaches 1.

The vestibule of the vagina until the 19th-20th week retains a pronounced funnel-shaped shape, covered with a smooth shiny membrane. In its depths, a barely protruding border of the hymen is determined.

Already by the 24-25th week, the vestibule is significantly flattened, and the hymen becomes available for measurement. Until 28-30 weeks, the hymen is often circular, and its opening has the shape of a collapsed longitudinal slit. The width of the hymen border reaches 2-3 mm.

After 30 weeks, there is a predominant growth of the lower semicircle of the hymen, a wedge-shaped protrusion is often found along the midline. At this level, the width of the lower part of the hymen is 5-7 mm. Its upper semicircle retains its former width, as a result of which the hole takes the form of a transverse crescent-shaped slot.

Timing of feminization of the external genitalia and endocrine activity of the fetal adrenal glands. In fetuses of 8-14 weeks, the fetal adrenal cortex is represented by a wide germinal zone with a narrow layer of undifferentiated cells of the definitive zone. Up to 11 weeks of pregnancy in the cells of the internal germinal zone, there is a high activity of acid and alkaline phosphatases and esterases. RNA is found in significant amounts in both zones. The content of lipids in the fetal zone is low; they are absent in the definitive cortex.

In fetuses of 12-14 weeks, the enzymatic activity and RNA content in the adrenal glands are reduced; the accumulation of lipids in the inner zone begins.

The stage of 15-17 weeks is characterized by differentiation of the definitive cortex according to the bundle type, which is accompanied by a further decrease in enzyme activity and a decrease in RNA in the cytoplasm.

Lipid deposits appear and rapidly grow in the cells of the outer zone. Their content in this zone remains high until the end of the antenatal period.

At 27-28 weeks, a glomerular zone is formed under the capsule of the gland.

By 34-35 weeks, there is an increase in the enzymatic activity of the adrenal cortex in parallel with an increase in cytoplasmic RNA, reaching a maximum level in the second half of intrauterine development.

Non-keto lipids of the definitive cortex are considered as C18 steroids: estradiol or estriol. In the second half of pregnancy, the level of estradiol in maternal and fetal blood is the same, while estriol in the fetus is 10 times higher than in the mother. Therefore, it is legitimate to consider C18-steroids of the outer zone of the fetal adrenal cortex as estriol responsible for the feminization of the female external genitalia in the antenatal period of ontogenesis.

In fetuses of 17-19 weeks, there is a rapid accumulation of lipids in the definitive zone of the adrenal cortex, and the external genitalia undergo feminization. By this time, there is a noticeable increase in the size of the fetal adrenal glands, their size exceeds (at this stage of development) the size of the internal genitalia of the fetus.

In the last stages of intrauterine life, the lipid content in the outer zone of the adrenal cortex remains high; in the external genitalia, feminization is completed and all parts of the vulva grow, except for the clitoris. Consequently, following the differentiation of the definitive fetal adrenal cortex in female fetuses, feminization and rapid growth of the external genitalia occur.

The development of the external genitalia of the fetus in the pathological course of pregnancy. Unfavorable conditions of intrauterine existence can disrupt the timing of morphogenesis. The state of the vulva in this case depends on the time and duration of the action of pathological factors. With long-term preservation of pathological conditions in 14.1% of cases, a lag (for a period of 2 to 17 weeks) in the development of the external genitalia was revealed. The short action of the damaging factor in 0.9% of cases contributes to earlier feminization of the genitals. Violation of the terms of morphogenesis of the vulva during the pathological course of pregnancy can be associated with a violation of steroidogenesis in the fetal adrenal glands, which manifests itself in a change in the accumulation of lipids in the definitive cortex.

Particularly noteworthy are cases of violations of the morphogenesis of the female external genitalia with prolonged use (during pregnancy) of large doses of progesterone.

In one of these cases, pregnancy from 4 weeks was complicated by the threat of termination. Progesterone treatment was performed at 8, 13, 16 and 18 weeks. On the 22nd week there was a spontaneous miscarriage. There is masculinization of the external genitalia of the female fetus.

It should be emphasized that the tissues of the genitals of the embryo and fetus are highly sensitive to the action of steroid hormones. Long-term use in the fetal period and in high doses of exogenous progesterone can disrupt fetal adrenal steroidogenesis, causing the production of excessive amounts of androgenic steroids responsible for masculinization of the external genitalia.

In the human embryo, indifferent internal and external genital organs are first laid, and then the internal and external male or female genital organs are formed in their final form.

The rudiments of the indifferent gonads in the human embryo appear in the wall of the body cavity at the 4th week of embryonic development from the rudiments of the epithelium, located anteriorly and medially from the anlages of the right and left primary kidneys, extending from the IV cervical to V lumbar segments of the body. On the 5th week, a groove is formed from the cells lining the body cavity. Then the groove deepens, its edges approach each other and it turns into the paramesonephric duct, which opens into the urogenital sinus. On the ventromedial surface of the primary kidney, the future sex gland begins to form. In this place, on each side of the root of the mesentery, a roller-like elevation is formed - the urogenital fold. Further, each of these folds is divided by a longitudinal groove into the medial part - the genital fold, where the gonad is then formed, and the lateral part, which is the primary kidney, as well as the duct of the primary kidney and the paramesonephric duct.

At week 7, the developing sex glands (gonads) begin to differentiate into either testes or ovaries. During the formation of the testes, the ducts of the primary kidneys turn into the excretory ducts of the male gonads, and the paramesonephric ducts are almost completely reduced. If the formation of the ovaries occurs, then the fallopian tubes, the uterus and part of the vagina develop from the paramesonephric ducts, and the ducts of the primary kidneys turn into rudimentary formations. The external genital organs are laid in the embryo at the 7th week of embryonic development in an indifferent form: in the form of a tubercle, genital folds and ridges. From these anlages, the external male or female genital organs then develop.

Development of the internal male reproductive organs

At the 7th month of intrauterine development, the albuginea is formed from the connective tissue surrounding the developing male gonad. By this time, the sex gland becomes more rounded, strands are formed in it, differentiating into the seminiferous tubules.

With the development of the male sex gland, the efferent tubules of the testis are formed from the tubules of the primary kidney, and the duct of the epididymis is formed from the cranial part of the duct of the primary kidney. Several cranially located tubules of the primary kidney turn into an appendage of the epididymis, and caudally lying tubules turn into an appendage of the testicle. From the rest of the duct of the primary kidney (caudal to the epididymis), around which the muscular membrane is formed, the vas deferens is formed. The distal part of the vas deferens expands and turns into an ampulla of the vas deferens, a seminal vesicle develops from the lateral protrusion of the duct. From the terminal narrowed section of the duct of the primary kidney, the ejaculatory duct is formed, which opens into the male urethra - the male urethra.

The cranial end of the paramesonephric duct is transformed into a testicular appendage, and the prostatic uterus arises from the merged caudal ends of these ducts. The rest of these ducts are reduced in male embryos.

The testicle with its appendage and rudimentary formations do not remain in the place where they were laid, but in the process of development they shift in the caudal direction - the process of lowering the testicles (descensus testis) occurs. In this process, the guiding ligament of the testis plays a major role. By the 3rd month of the intrauterine period, the testicle is located in the iliac fossa, by the 6th month it approaches the inner ring of the inguinal canal. At the 7-8th month, the testicle passes through the inguinal canal along with the vas deferens, vessels and nerves, which are part of the spermatic cord formed during the descent of the testicle.

The prostate gland develops from the epithelium of the emerging urethra in the form of cell strands (up to 50), from which gland lobules are subsequently formed. Bulbourethral glands develop from epithelial outgrowths of the spongy part of the urethra. The ducts of the prostate gland and bulbourethral glands open with their mouths in those places where the laying of these glands occurred in the process of intrauterine development.

Development of the internal female genital organs

In the ovary of the female embryo, the zone of connective tissue under the layer of rudimentary epithelium is less pronounced than in the male gonad. Cell strands are less visible, germ cells are scattered in the mesenchymal stroma of the organ. Some of these cells grow more actively, they become larger, surrounded by smaller cells, the initial - primordial - ovarian follicles are formed. Subsequently, the cortical and medulla of the ovary is formed. Blood vessels and nerves grow into the latter. As they develop, the ovaries also descend, but at a much shorter distance than the testicles. From the place of laying, the ovaries are displaced together with the fallopian tubes into the pelvic region. The descent of the ovaries is accompanied by a change in the topography of the fallopian tubes, which pass from a vertical position to a horizontal one.

With the development of the ovary, the remaining tubules and duct of the primary kidney become rudimentary - appendages of the female sex gland. The cranially located tubules and the adjacent part of the duct turn into the epididymis of the ovary (the supraovary), and the caudal ones into the periovary. The remnants of the duct of the primary kidney can be preserved in the form of a continuous or intermittent strand lying on the side of the uterus and vagina - this is the longitudinal duct of the ovarian epididymis (Gartner's canal; ductus epoophori longitudinalis).

The fallopian tubes develop from the paramesonephric ducts, and the uterus and the proximal vagina are formed from the distal, fused parts. From the urogenital sinus, the distal vagina and its vestibule are formed.

Development of the external genitalia

On the 3rd month of intrauterine development, anterior to the cloacal membrane from the mesenchyme, a genital tubercle appears. At the base of the genital tubercle towards the anus is the urogenital (urethral) groove, which is limited on both sides by the genital folds. On both sides of the genital tubercle and genital folds, semilunar forms of elevation of the skin and subcutaneous tissue are formed - genital ridges. These formations represent the indifferent anlage of the external genital organs, from which the external male or female genital organs develop in the future.

Development of the external male genitalia

In male embryos, indifferent rudiments undergo complex changes. The genital tubercle begins to grow rapidly and lengthen, turning into the cavernous bodies of the penis. On their lower (caudal) surface, the genital folds become higher. They limit the urogenital (urethral) gap, which turns into a groove. Then, as a result of the fusion of the edges of the groove, the male urethra and the spongy body of the penis are formed. In the process of growth, the urogenital opening from its original position at the root of the penis, as it were, moves to its distal end.

The place of closure (fusion) of the urethral groove remains in the form of a scar, called the suture of the penis. Simultaneously with the formation of the male urethra, the foreskin is formed above the distal end of the penis. This is due to the development of a skin fold around the head of the penis.

The genital folds become more convex, especially in the caudal regions, they converge and fuse along the midline. At the site of fusion of the genital ridges, a scrotal suture arises, which stretches from the root of the penis to the anus through the entire perineum.

Development of the external female genital organs

In female embryos, the genital tubercle transforms into the clitoris. The genital folds grow and turn into the labia minora, which laterally limit the urogenital fissure, which opens into the urogenital sinus. The distal part of the genital slit becomes wider and turns into the vestibule of the vagina, where the female urethra and vagina open. The opening of the vagina by the end of fetal development becomes much wider than the opening of the urethra. The genital folds are transformed into the labia majora, in which a significant amount of fatty tissue accumulates, then they cover the labia minora.