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THE GENITAL DUCTS. Dr. Nimir Dr. Safaa. Objectives: Describe and discuss the development of epididymis and vas deferens. Describe and discuss the development of the uterus and fallopian tubes. Discuss the congenital anomalies of epididymis , vas deferens and mesonephric duct.
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THE GENITAL DUCTS • Dr. Nimir • Dr. Safaa
Objectives: • Describe and discuss the development of epididymis and vas deferens. • Describe and discuss the development of the uterus and fallopian tubes. • Discuss the congenital anomalies of epididymis , vas deferens and mesonephric duct. • Discuss the congenital anomalies of the uterus, fallopian tubes and paramesonephric duct.
Initially, both male and female embryos have two pairs of genital ducts: mesonephric (wolffian) ducts and paramesonephric (müllerian) ducts. • The paramesonephric duct arises anterolateral to the urogenitalridge. • Cranially, the duct opens into the abdominal cavity. • Caudally, it first runs lateral to the mesonephricduct, then crosses it and fuse with the other duct to form the uterine canal. • The tip of the fused ducts projects into the posteriorwallof the urogenitalsinus to form the paramesonephric(müllerian)tubercle.
Genital Ducts in the Male • As the mesonephrosregresses epigenitaltubules connect retetestis andform the efferent ductules. • Paragenitaltubules, do not join retetestis and their vestiges are theparadidymis. • Except for the appendix epididymis, the mesonephric ducts persist and under the influence of testosteron form the main genital ducts.
Below the entrance of the efferent ductules, mesonephricducts elongate and become highly convoluted, forming epididymis. • From the tail of epididymis to seminal vesicle,mesonephricducts form ductusdeferens. • The region of the ducts beyond the seminal vesicles is the ejaculatory duct. • Under the influence of antimullerian hormone (AMH) produced by sertoli cells, paramesonephric ducts in the male degenerate except for a small portion at their cranial ends, the appendix testis.
Genital Ducts in the Female: • The paramesonephric ducts develop into the main genital ducts of the female. • Initially, three parts can be recognized in each duct: • (1) a cranial vertical portion that opens into the abdominal cavity. • (2) a horizontal part that crosses the mesonephric duct. • (3) a caudal vertical part that fuses with its partner from the opposite side. • The firsttwo parts develop into the uterine tube, and the caudal parts fuse to form the uterine canal.
After the ducts fuse in the midline, a broad transverse pelvic fold is established. This fold, which extends from the lateral sides of the fused paramesonephric ducts toward the wall of the pelvis, is the broad ligament of the uterus. • The fused paramesonephric ducts give rise to the corpus and cervix of the uterus.
Vagina: • After the paramesonephricducts reaches the urogenital sinus , two solid evaginations grow out from the pelvic part of the sinus. • These evaginations, the sinovaginalbulbs, proliferate and form a solid vaginal plate. • By the fifth month, the vaginal outgrowth is entirely canalized. • The vaginal fornicesare of paramesonephricorigin. • Thus, the vagina has a dual origin, with the upper portion derived from the uterine canal and the lower portion derived from the urogenital sinus.
The lumen of the vagina remains separated from that of the urogenital sinus by a thin tissue plate, the hymen . It usually develops a small opening during perinatal life. • The female may retain some remnants of the cranial and caudal excretory tubules in the mesovarium,wherethey form the epoophoronandparoophoron, respectively . • The mesonephric duct disappears except for a small cranial portion found in the epoophoron, and occasionally a small caudal portion in the wall of the uterus or vagina. Later in life, it may form Gartner’s cyst.
Uterine abnormalities arise from fusion malformations. Two uteruses and two vaginas (there was no fusion of the ducts at all.) Double uterus, one vagina( partial fusion).
