Development of Reproductive system-FB (1).pptx

embryologic development of the reproductive organ

1. Development of Reproductive system By: Fikre Bayu

2. The genital system consists of: a pair of gonads (testes or ovaries) duct system of gonads that carries the germ cells external genital organs. The genetic sex (genotype XY or XX) of embryo is established at time of fertilization, but gonads do not acquire male or female morphological characteristics till 7 th week of the development. Sex is determined: Genetically at the time of fertilization Phenotypically by the 7 th week depending on several factors. The testis and ovary are not identifiable histologically until 10 th week Introduction

3. Developments of Gonads from three sources Primordial germ cells Intermediate mesoderm Coelomic epithelium covering intermediate mesoderm Introduction…

4. Indefinitive stage At this time testis and ovary similar From the genital(Gonadal) ridges Located between mesonephros and dorsal mesentery. Epithelium of gonadal ridges proliferate and project into the mesenchyme giving the primary sex (gonadal) cords Development of the indifferent gonads

5. Has outer cortex and inner medulla Differentiations into testis or ovary depend on the genetic sex chromosome make-up of the primordial germ cells . Development of the indifferent gonads…

6. Large spherical cells that develop from the endodermal cells in the wall of the yolk sac near allantois . Incorporated into the sex cords by the 6 th week by migrating via dorsal mesentery of the hindgut. N.B . If the primordial germ cells fail to reach the genital ridges, gonads do not develop. Thus, primordial germ cells have an inductive influence on the development of gonads into testis or ovary. Primordial Germ cells.

7. Blastocyst Inner cell mass ( epiblast ) PGCs Migration of PGCs to gonads Gametogenesis 5 th week 4 th week Yolk sack Amoeboid mov't Mitotic division Supporting cell Gonadal ridge 1 2 Primordial Germ cells.

8. The indifferent gonad develops into testis or ovary depending upon the chromosome complement of the primordial germ cells . If the primordial germ cells carry XY sex chromosome complement the indifferent gonad will develop into testis If the primordial germ cells carry XX chromosome complement the indifferent gonad will develop into an ovary Definitive stage

9. Testis-determining factors(TDF) located on the short arm of the Y (SRY) chromosomes of the primordial germ cells dictate differentiation of the indifferent gonads into the testes they cause: Regression of the cortex of the indifferent gonads. Condensation of the sex cords forming the seminiferous or testicular cords and their movement towards the medulla . Seminiferous or testicular cords branch and anastomose forming rete testis in the medulla. N.B: Master gene for development of testes = SRY gene Development of Testes

10. Seminiferous cords will give rise to intratesticular genital ducts: 1. Seminiferous tubules- lined by: A. Spermatogonia derived from the primordial germ cells B. Sertoli cells derived from the epithelial cells of the sex cords Remain solid until the lumina begin to develop by puberty . 2. Tubuli recti 3. Rete testis- developing from the anastomosis of the seminiferous cords . Mesenchyme located in between the seminiferous cords will give to the interstitial cells ( Leydig cells). Development of Testis …

11. Development of the testis…

12. Influence of primordial germ cells on indifferent gonad

13. In the absence of Y chromosome , under the influence of genes on x chromosomes the indifferent gonads develop into the ovaries . The primary sex (gonadal) cords become rudimentary and move into the medulla as rete ovarii and gradually degenerate. Secondary sex (gonadal or cortical) cords develop from the surface epithelium into the underlying mesenchyme. N.B. The X chromosomes bear genes for ovarian development . Development of the Ovaries

14. The secondary sex cords Are invaded by the primordial germ cells and broken down into primordial follicles , made by: Oogonia , derived from a primordial germ cell A single layer of flattened follicular cells derived from the surface epithelium. The ovary separates from the regressing mesonephros , and will be suspended by a mesentery known as the mesovarium. Development of the Ovaries…

15. Development of the ovaries…

16. During the 5 th and 6 th weeks there are paired ducts in both sexes . The differentiation of genital ducts and external genitalia is influenced by the gonads. 1. Right and left mesonephric (Wolffian) ducts = “Wondwosen” It form definitive genital ducts in male It is disappear in female 2. Right and left paramesophric ( M ü llerian) ducts = “ Mulunesh ” It form definitive genital ducts in female It is disappear in male Development of the indifferent Genital Ducts

17. By longitudinal invaginations of the mesothelium Located lateral to the mesonephric ducts and the gonads . Have funnel-shaped cranial ends that open into the peritoneal cavity . Development of Paramesonephric (Müllerian duct

18. Run parallel to the mesonephric ducts and at the level of future pelvis cross medially over the mesonephric ducts to fuse with each other to form a Y-shaped uterovaginal primordium which: Projects into the dorsal wall of the urogenital sinus = U. Bladder Initiates the formation of the sinus (M ü llerian or paramesonephric) tubercle. Development of Paramesonephric (Müllerian duct

19. At 6-7 week , the Sertoli cells to produce M ü llerian inhibiting substance or factor ( MIS or MIF ), also known as anti M ü llerian hormone (AMH) and suppresses the differentiation of M ü llerian ducts . By the 8 th week , the cells of Leydig begin producing testosterone that stimulates differentiation of: 1. Mesonephric tubules to the efferent ductules of the testes 2. Mesonephric ducts to : a. Ductus epididymis b. Ductus deferens c. Ejaculatory ducts d. Seminal vesicles (glands) Development of Male Genital duct

20. Influence of the sex glands on further sex differentiation

21. Prostate gland and bulbourethral glands develop from the endodermal epithelium lining respectively, prostatic urethra and spongy part of the urethra. Seminal gland /vesicle / develop as outgrowth from caudal end of mesonephric duct . Development of Male Accessary Genital Glands

22. In the genetically female embryos : 1 . Lack of testosterone stimulation causes degeneration of mesonephric ducts . 2. lack of M ü llerian inhibiting substance cause passive development of: a. Uterine(fallopian) tubes from the cranial unfused parts of paramesonephric ducts. b. Uterus develops from the cranial portion of the uterovaginal primordium . c. Cranial 3 rd of vagina from caudal portion of the uterovaginal primordium Development of Female Genital duct& glands

23. Uterovaginal primordium Projects into the dorsal wall of the urogenital sinus Initiates the formation of the sinus (M üllerian) tubercle which: Induces development of paired sinovaginal bulbs from the urogenital sinus extending to the caudal end of Uterovaginal primordium . Paramesonephric (M üllerian) ducts

24. The sinovaginal bulbs fuse and form a solid vaginal plate which gets canalized and gives rise to the epithelium of lower 2/3 rd of the vagina . Cranial 1/3 rd of vagina develops from caudal portion of the Uterovaginal primordium . Development of the vagina

25. Influence of the sex glands on further sex differentiation

26. Hymen By invagination of the posterior wall of the urogenital sinus and expansion of the caudal end of vagina. Separates vaginal lumen from urogenital sinus. Ruptures prenatally and remains as a thin fold of mucous membrane just within the vaginal orifice. Development of the vagina…

27. Urethral glands and paraurethral glands(of Skene , which correspond to the prostate gland ) develop as buds from the urethra. Greater vestibular glands of Bartholin , which correspond to bulbourethral glands ) develop as buds from the urogenital sinus . Lesser vestibular glands develop from the urogenital sinus . Development of the female Accessary Glands

28. Are similar in both sexes up to the 7 th week , with: 1. Genital tubercle Gives rise phallus at the cranial end of cloacal membrane. 2. Urogenital (urethral) folds Bound the urethral groove lined by endodermal cell , and vestibule when the urogenital membrane ruptures by late 7 th week . 3. Labioscrotal (genital) folds or swellings) Just lateral to the urogenital folds Distinguishing sexual characteristics begins to appear by the 9 th week to be fully differentiated by 12 th week . Indifferent external genitalia

29. Fig. C,D. 9wk , Fig. E,F. 11wk Fig. G,H. 12wk

30. Lack of testosterones and influence of estrogen from the ovaries cause development of the indifferent external genitalia into the female external genitalia 1 . Failure of phallus to grow giving rise to the clitoris . 2. Urogenital folds Largely fails to fuse giving rise to labia minora Posteriorly fused giving rise to the frenulum of labia minora 3 . Labioscrotal folds Largely fails to fuse giving rise to the labia majora Fuse anteriorly and posteriorly giving ,respectively the anterior labial commissure and mons pubis , and posterior commissure . Development of female external genitalia

31. Descend from the posterior abdominal wall to pelvis, but arrested just below the rim of true pelvis. Gubernaculum Is attached to the uterus near the uterine tube. Cranial part of the becomes the ovarian ligament Caudal part forms the round ligament of the uterus and extends to the labia majora via the inguinal canals. Processus vaginalis is small and disappears. A processus vaginalis that persists after birth is called a canal of Nuck . Descent of Ovaries

32. Appendix of the epididymis By cranial end of the mesonephric duct Usually attached to head of epididymis 2 . Paradidymis By some caudal mesonephric tubules Vestigial remnants of Mesonephric Ducts in Male

33. 1 . Appendix of the testis By cranial end of the paramesonephric duct attached to the superior pole of the testis. 2 . Prostatic utricle A small saclike structure that opens into seminal colliculus in the prostatic urethra Homologous to the vagina 3 . Seminal colliculus A small elevation in the posterior wall of the prostatic urethra From sinus tubercle Homologous to the hymen Vestigial remnants of Para Mesonephric Ducts in Male

34. 1. Appendix vesiculosa By cranial end of mesonephric duct 2 . Epoophoron A few blind ended tubules and a duct within the mesovarium between ovary and uterine tube. Correspond to the efferent ductules and duct of the epididymis in the male . Vestigial remnants of Mesonephric Duct in females

35. 3 . Paroophoron Rudimentary tubules located closer to uterus By remnants of mesonephric tubules 4. Duct of Gartner By parts of the mesonephric duct between the layers of the broad ligament along the lateral wall of the uterus and in the wall of the vagina . Correspond to the ductus deferens and ejaculatory duct in the male. Vestigial remnants of Mesonephric Duct in females

36. Hydatid (of Morgagni) Part of the cranial end of the paramesonephric duct that does not contribute to the infundibulum of the uterine tube may persist as a hydatid (of Morgagni) . Vestigial remnants of Para mesonephric Duct in females

37. Embryonic structure & Adult derivatives

38. Congenital Anomalies in the development of the genital system

39. Discrepancy between the morphology of the gonads and the appearance of the external genitalia= Person who is both a male and a female at the same time Classified according to the histological appearance of the gonads True hermaphrodites have ovarian and testicular tissue either in the same or in opposite gonads= ovotestis . Female pseudohermaphrodites have ovaries. Male pseudohermaphrodites have testes. Pseudohermaphrodite = Individual with gonads of one sex and external genitalia of other sex Hermaphroditism (Intersexuality)

40. Have both ovarian and testicular either in the same or in opposite gonads that are nonfunctional. About 70% have 46 XX , 20% have 46,XX/46,XY mosaicism (presence of two or more cell lines), while 10% have a 46,XY chromosome constitution. An ovotestis (containing both testicular and ovarian tissue) forms if both the medulla and cortex of the indifferent gonads develop. Caused by error in sex determination . With ambiguous external genitalia , or predominantly female external genitalia , and hence most are brought up as female . Rare True Hermaphrodities

41. True hermaphrodites A 17-year-old true hermaphrodite with bilateral scrotal ovotestes and a 46,XX sex chromosome constitution Perineal hypospadias Moderate bilateral gynecomastia and pubic hair Sparse axillary hair, a high-pitched voice, and absent facial hair.

42. With 46,XX and have ovaries. By increased levels of androgens, commonly because of congenital adrenal hyperplasia (CAH, adrenogenital syndrome) Show Clitorial hypertrophy Partial fusion of labia majora Small persistent urogenital sinus Female pseudohermaphrodities Fig. External genitalia of a 6-year-old girl showing an enlarged clitoris and fused labia majora that have formed a scrotum-like structure. The arrow indicates the opening into the urogenital sinus.

43. With 46, XY and have testes By reduced levels of testosterone and MIF resulting in inadequate virilization showing variable development of external and internal genitalia Androgen insensitivity syndrome (AIS, testicular feminization syndrome) With 46 XY, but normal appearing female and hence not intersex. Male pseudohermaphrodities

44. Androgen insensitivity syndrome (AIS, testicular feminization syndrome) Has female external genitalia , vagina that usually end blindly, and no or rudimentary uterus and uterine tube . By resistance of external genitalia to testosterone because of defect in the androgen receptor mechanism and influence of estrogen towards the female. Show normal development of breast and female characteristics, but no menstruation , and absent or scanty pubic hairs. Undescended testes usually in abdomen or inguinal canal , or may be found in labia majora • Socially, mentally, and psychologically the women with AIS are entirely female . • Embryologically these females represent an extreme form of male pseudohermaphroditism . Male pseudohermaphrodities…

45. With mosaic 45 x and xy Has dysgenic testis on one side and undifferentiated gonad on the other side . Show female internal genitalia, and also sometimes with male derivatives of the mesonephric ducts. External genitalia varies from normal female, intermediate or normal male . No breast or menstruation, but varying degrees of virilization Mixed gonadal dysgenesis

46. Klinefelter’s syndrome It is the most common major abnormality of sexual differentiation occurring in 1/500 births. A karyotype of 47XXY . The most common cause is nondisjunction of XX homologues. The characteristic clinical features are : Hypogonadism associated with testicular atrophy Infertility Gynecomastia Eunuchoid habitus Elevated gonadotrophin levels Poorly developed secondary sexual characters Klinefelter’s syndrome

47. Testis is located in the abdominal cavity or anywhere along the path of descent of testis, but usually in the inguinal canal Unilateral or bilaterally Occurs in 30% of premature males and 3-4% of full-term males. Cause is unknown, but reduced level of androgen is an important factor N.B. In case of cryptorchidism testicular hormones are used to promote the descent. If it fails, the testes are surgically mobilized and fixed to the scrotal floor ( orchidopexy (OR-kid-o- pex - ee )). Cryptorchidism or undescended testis

48. Because of the gubernaculum taking an abnormal direction leading testis to wrong location : Interstitial(external to aponeurosis of external oblique muscle) In the proximal part of medial aspect of thigh Dorsal to the penis On the opposite side as crossed ectopia Ectopic testis

49. By persistent communication between tunica vaginalis and peritoneal cavity Herniation of a loop of intestine into the scrotum or labium majus More common in males , especially when there are undescended testes or ectopic testes Congenital Inguinal Hernia

50. When the abdominal end or part of processus vaginalis remained open, but is too small to permit herniation of intestine. Peritoneal fluid accumulates and cause hydrocele of testis(scrotum) and spermatic cord . Bilaterally /unilaterally Hydrocele

51. When the urethra opens ventrally By reduced levels of androgens ( or their receptors) causing failure of canalization of gonadal plate and /or fusion of urogenital folds resulting in incomplete formation of spongy urethra . Penis is usually underdeveloped and curved ventrally (as chordee ) Hypospadias

52. Four types: Glanular hypospadias- when open on ventral surface of glans penis , and is the most common type (in 1 of every 300 male infants). Penile hypospadias- when open on ventral surface of body of penis. Penoscrotal – when open at the junction between penis and scrotum Perineal Unfused labioscrotal folds Urethral orifice located between the halves of scrotum When associated with crytorchidism could be misdiagnosed as male pseudohermaphrodites . Hypospadias…

53. Urethral orifices opens dorsally Often associated with extrophy of the urinary bladder May be by development of the genital tubercle more dorsally in the region of urorectal septum Epispadias

54. When genital tubercle has not developed Urethra opens into perineum near anus. Micropenis By reduced levels of androgens Commonly associated with hypopituitarism or hypogonadism. Bifid penis Usually associated with extrophy of urinary bladder. Double penis From development of two genital tubercles Agenesis of the Penis

55. When inferior part of Paramesonephric ducts fail to fuse Could be associated with double or single vagina Bicornuated uterus (uterus bicornius ) When the duplication involves only the superior parts of the body of uterus Double uterus (Uterus didelphys)

56. Bicornuate uterus with a rudimentary horn( cornu ) When one paramesonephric duct may be retarded and does not fuse with the other . Unicornuate uterus Uterus with one uterine tube By the failure of one paramesonephric tube to develop Double uterus (Uterus didelphys)

57. By failure of paramesonephric duct development Absence of uterus means lack of induction of development of sinovaginal plate leading to absence of development of vagina Double vagina When sinovaginal bulbs fail to fuse Absence of uterus

58. It is vaginal blockage By failure of canalization of vaginal plate When sinovaginal bulbs fail to develop Vaginal atresia

59. Variations in the appearance of the hymen End