114 



HUMAN EMBRYOLOGY AND MORPHOLOGY. 



process may be arrested at this stage — a stage shown by some 

 adult marsupials. Then the lower or vaginal part of the septum 

 disappears; the human uterus then (3 \ months) resembles that 

 of higher mammals (carnivora, etc., Fig. 88. G). It may be 

 arrested at this stage (uterus bicornis). Lastly the upper part 

 of the septum disappears (4| months, Fig. 89). The fundus, 

 which is the last part to be developed and is only found in the 

 highest primates, is quite well marked in the child at birth. 



from right i 

 Muller. duct} 



Fa/fop. tube 



fast part to disappear 

 from left Muller. duct. 



1st part to disappear 

 3rd month 



(2nd part of septum to 

 1 disappear 



Fig. 89. — Showing the manner in which the Mulleriau Ducts fuse to form the Uterus 

 and Vagina. 



The lining epithelium of the lower third of the vagina is 

 derived, according to the researches of Berry Hart, from the 

 lower ends of the Wolffian ducts. A solid epithelial bud (epi- 

 blast) grows from the end of each duct, and fills the lower part 

 of the united Miillerian ducts. The central cells of the Wolffian 

 buds disappear, while the peripheral form the lining of the lower 

 third of the vagina. 



The Miillerian Ducts in the Male. — All that remains of the 

 Miillerian ducts in the adult male are their fused terminal seg- 

 ments forming the sinus pocularis or uterus masculinis in the 

 prostate (Figs. 82 and 90). Its depth is commonly about 3 or 

 4 mm., but occasionally such a form as is represented in Fig. 91 



