426 THE KABBIT. 



duct grows slowly backwards, but does not reach the level of 

 the urino-genital sinus until about the twentieth day. 



5. The Genital Ducts and Accessory Genital Organs. 



In the male, or buck rabbit, outgrowths from the tubules of 

 the Wolffian body penetrate into the testis at a very early stage 

 of development, forming the tubuliferous tissue already described, 

 and giving rise ultimately to the vasa efferentia. The Wolffian 

 body becomes greatly reduced in size, and is converted into the 

 head of the epididymis ; the proximal part of the Wolffian duct, 

 which is greatly convoluted, gives rise to the body and tail of 

 the epididymis (Fig. ICO, w) ; and the distal part of the duct 

 forms the vas defer ens, x. 



The testes originally lie opposite the anterior ends of the 

 Wolffian bodies, and attached to the dorsal wall of the abdomen ; 

 ultimately they shift their position from the dorsal to the ventral 

 wall of the abdomen, and, passing through the inguinal rings, 

 become lodged in a pair of pouch-like folds of the skin, the 

 scrotal sacs (Fig. 160). 



The Miillerian ducts, in the male rabbit, disappear completely. 

 The uterus masculinus (Fig. 160, s)has been stated to be formed 

 from their hinder or distal ends, but according to Kolliker it 

 is derived from the Wolffian, and not from the Miillerian ducts ; 

 these latter in the male never opening into, or even reaching, the 

 urino-genital passage. 



In the female, or doe rabbit, the Miillerian ducts become 

 greatly enlarged, and form the oviducts. Their abdominal 

 openings persist as the open fimbriated mouths of the Fallopian 

 tubes ; the proximal portions of the ducts become the Fallopian 

 tubes themselves ; the middle portions become the uteri ; and 

 the terminal, or distal segments unite to form the vagina. 



The Wolffian bodies, in the female, undergo degenerative 

 changes ; they become greatly reduced in size, and are ultimately 

 converted into the parovaria. The Wolffian ducts either 

 disappear completely, or else small portions of them persist as 

 rudimentary or vestigial structures. 



