Presentation on theme: "DEVELOPMENT OF MALE & FEMALE GENITAL SYSTEM"— Presentation transcript:
1DEVELOPMENT OF MALE & FEMALE GENITAL SYSTEM ByDr Samina Anjum
2DEVELOPMENT OF GONADSSex of the embryo is determined genetically at the time of fertilization.Type of gonads present then determines the type of sexual differentiation that occurs in the genital ducts and external genitalia.Gonads do not acquire male or female morphological characteristics until the 7th week of development.
3Gonadal / Genital ridge The gonads (testes and ovaries) are derived from three sources : Mesothelial lining the posterior abdominal wall Condensation of underlying mesenchyme (embryonic connective tissue) Primordial germ cells
4Migration of primordial germ cells into developing gonad .
5Primordial germ cellsArrive at the beginning of 5th week
6Invade the genital ridges in the 6th week. Inductive influence
7Indifferent GonadsFinger like primitive sex cords appear, grow into underlying mesenchyme, but remained connected to surface epithelium.Consist of:External cortexInternal medulla.
9Development of the Testis SRY gene & TDFPrimitive sex cords proliferate, penetrate deep into Medulla to form the testis / Medullary cordsTowards the hilum, the cords break up into tubules of rete testis.The gonadal cords –looses connection with the surface epithelium when thick fibrous capsule develops, tunica albuginea.
10Spermatogonia -primordial germ cells 4th month testis cords become horse shoe shaped and connect with rete testis.Spermatogonia -primordial germ cellsSertoli cells- the surface epithelium.Interstitial cells of Leydig- mesenchyme-Testosterone By 8th weeks
11Cont…. Testis cords remain solid till puberty. Acquire lumen forming seminiferrous tubules.Once canalized join rete testis which enter ductuli efferentes ---mesonephric duct
12Derivatives The testis cords develop into: the seminiferous tubules rete testis.Mesenchyme between the seminiferous tubules providethe interstitial cells of Leydig.
14DEVELOPMENT OF OVARY Degeneration of Primitive/ medullary sex cords Formation of cortical cords, dissociate into irregular cell clusters which occupy the medullary part of the ovary.Later, they disappear & replaced by a vascular stroma that forms the ovarian medulla.
157th week, surface epithelium proliferate Formation of second generation of cords, cortical cords, which remain close to the surface.4th month, cords split into isolated cell clusters, which surrounds PGCs.Formation of oogonia & the follicular cells.
21Paramesonephric ducts arise as a longitudinal invagination of the epithelium on the anterolateral surface of the urogenital ridge.Cranially, the ducts open into the abdominal cavity with a funnel-like structure.Caudally, it first runs lateral to the mesonephric duct, then crosses it ventrally to grow caudomedially.
22Close contact with the duct of opposite side. Separated by a septum, later forms the uterine canal.The caudal tip of the combined duct projects into the posterior wall of the urogenital sinus, the paramesonephric or müllerian tubercle.Mesonephric ducts open on each side of urogenital sinus
23Development of Male Genital Ducts Ejaculatory ductAt 4th monthAfter descent of testis
24GENITAL DUCTS IN THE FEMALES End of 2nd monthAfter descent of ovary
25When the 2nd part moves mediocaudally, the urogenital ridges come to lie in the transverse plane creating a horizontal fold the broad ligament of the uterus.
26DERIVATIVES Fused paramesonephric ducts give rise to: Body of uterus CervixUpper part of vaginaSurrounded by:Mesenchyme ---- MyometriumPeritoneum ---- Parametrium
27DEVELOPMENT OF VAGINAShortly after the solid tip of the paramesonephric duct reaches the urogenital sinus, two solid evaginations grow out from the pelvic part of the sinus.These sinovaginal bulbs proliferate to form a solid vaginal plate.
28By the 5th month, the vaginal outgrowth is entirely canalized. The wing-like expansions of the vagina around the end of the uterus, the vaginal fornices, are of paramesonephric origin.
38DEVELOPMENT OF PROSTATE GLAND Endodermal outgrowths from prostatic urethraSmooth m and stroma derived from surrounding mesenchymeProstatic utricle is a sac like structure that opens into prostatic urethra, is homologous to vaginaThe lining of Prostatic utricle is derived from epithelium of urogenital sinus.
39DEVELOPMENT OF FEMALE GENITAL GLANDS (Outgrowths of urogenital sinus)
40Development of External Genitalia UndifferentiatedExternal Genitalia(3rd to 6th Week)Female ExternalGenitaliaMale ExternalGenitalia
42Development of Male External Geniatlia 1.The indifferent external genitalia are masculinized by the testosterone The rapid elongation of genital tubercle into phallus The phallus pulls the urethral folds forward so that they form the lateral walls of urethral groove.4. The urethral groove extends along the caudal aspect of the elongated phallus but does not reach the most distal part, the glans. The groove is lined by endodermal epithelium and forms the urethral plate.
445. At the end of 3rd month, the two urethral folds close over the uretheral plate, forming the penile urethra.6. The most distal portion of urethra is formed during the 4th month, when ectodermal cells from tip of glans penetrate inward and form a short epithelial cord. This cord later forms lumen thus forming external urethtral meatus.7. The labioscrotal swellings fuse to form the scrotum.8. The line of fusion form the scrotal septum.
45EXTERNAL GENITALIA IN FEMALES Estrogens stimulate the development of external genitalia in females.Genital tubercle ---- ClitorisUrethral folds do not fuse ---- labia minoraGenital swellings enlarge ---- labia majoraUrogenital groove is open ---- vestibule
46DESCENT OF TESTISTowards the end of 2nd month urogenital mesentery attaches the testis and mesonephros to the posterior abdominal wall. Thus testis begin as retroperitoneal structures in the posterior abdominal wallWith degeneration of Mesonephros the attachment serves as mesentery for the gonads.
47Caudally urogenital mesentery becomes ligamentous and forms caudal genital ligament. Also extends from the caudal pole of testis is a mesenchymal condensation, the gubernaculum.Caudal genital ligament and
48Two parts of gubernaculum can be seen: Intraabdominal portion: grows prior to descent of testis and terminates in inguinal regionExtraabdominal portion: grows as testis begins to descend from inguinal region towards the scrotal swelling. When testis pass through inguinal canal this part contacts the scrotal floor
49As the gubernaculum "pulls" the testes into the pelvis and developing inguinal canal, it is preceded by the processus vaginalis, evagination derived from the peritoneum which lies anterior to the testes. Once testis are in scrotum the gubernaculum persist as scrotal ligament.
50Formation of inguinal canal The processus vaginalis accompanied by muscular and facial layers of anterior abdominal wall evaginates into scrotal swellings forming inguinal canal.Testis are then covered by a reflected fold of processus vaginalis having parietal and visceral layers. The narrow canal connecting the lumen of the vaginal process with the peritoneal cavity is obliterated at birth.
60HypospadiasHypospadias most common abnormality (1 in 300) from a failure of male urogenital folds to fuse in various regions and resulting in a proximally displaced urethral meatus. External urethral orifice is on ventral surface of glans or body.
61EPISPADIAS 1/30000 male infants Urethra opens on dorsal surface Associated with exostrophy of bladder.