214 



UROGENITAL SYSTEM 



Hind-gut 



Mesonephric 

 duct 



Allanfois 

 Cloaca 



■Cloaca! membrane 



i/lllantois 



'loacal membrane 



Tail-gut 



C loacal T 

 membrane 

 \Taib-gu.t 



Fig. 2og. — Four stages showing the differentiation of the cloaca into the rectum, urethra and blad- 

 der. A, from an embryo of 3.5 mm.; B, a somewhat later stage; C, from a 5 mm. embryo; D, from an 

 embryo of 7 mm. (after reconstructions by Pohlman). About 100 diameters. 



Mesonephric duct 

 Metanephros 



Intestine 



Anlaqe of bladder 



Ureter 



Cloacal 

 membrane 



Urogenital sinus 

 flee turn 



Fig. 210. — Reconstructions from a 12 mm. embryo showing the partial subdivision of the cloaca into 

 rectum and urogenital sinus (after Pohlman). 



