VAN 211: Veterinary Histology and Embryology (2+2)

MULLERIAN DUCTS

Both sexes develop a pair of female ducts of Muller. But its fate in the two sexes is different, as described below:

Female

• These ducts arise by formation of a groove in the thickened epithelium of the urino-genital ridge which is lateral to the mesonephros near its cranial end. This extreme cranial end of the groove remains open like trumpet while caudally the lips of the groove fuse into a tube.
• In the most posterior part, the two Mullerian ducts approach each other, reach the dorsal wall of the urogenital sinus, fuse and end blindly at the Muller’s tubercle-a median projection in the dorsal wall of the cloaca, caused by the opening of the mesonephric ducts into it. This fused region is the first indication of the uterus and vagina and the unfused cranial parts serve as uterine tubes.
• The fused part, by unequal growth of its walls, becomes trans formed into the uterus and vagina. The cranial end of the tube, which remains open, forms the fimbriated end of the fallopian tube. The Muller’s tubercle becomes the site of hymen.

Male

• The same primordia also develop but remain rudimentary. Degeneration of the ducts occurs in the third month and only the extreme cranial end is spared which remains as a vestige-the appendix testis.
• The portion which forms the uterus and vagina persists in a rudimentary from as the uterus masculinus.
• The Muller’s tubercle is represented by the colliculus seminalis.