THE UROGENITAL SYSTEM 



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tons," to which the placenta is attached. In the non-gravid 

 uterus they average about H inch in length, and a little less 

 in width and thickness. During pregnancy they become greatly 

 enlarged and pedunculated and may measure as much as 5 

 inches in length. 



Fig. 51. — Cross-section of mammary gland of cow: u, body of gland; 6, 

 lactiferous sinus; c, cavity of teat; d, teat canal; e, intermammary groove; /, 

 septum between glands; g, supermammary fat. (Sisson, Anatomy of Domestic 

 Animals.) 



The vagina is a tubular organ which connects the uterus and 

 the vulva. It is about 10 inches long, and is lined with mucous 

 membrane thrown up into folds that are effaced when the fetus 

 is passed. The os uteri projects freely into the fore part of the 

 vaginal cavity. 



The vulva is the passage that continues the vagina backward, 



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