the placenta makes such function unnecessary. Degenera- 

 tion of the mesonephros sees part of its structure modified 

 into sexual ducts: epididymis and vas deferens in the male, 

 the epobphoron and Gartner's duct in the female (Figure 

 10-35). 



Reptiles and birds 



The adult kidney of the turtle, Sphenodon, or lizard is a 

 metanephros of relatively small size, lying well back in the 



body cavity (Figure 10-8). The shape of the kidney reflects 

 somewhat the body shape; long and thin in snakes, short 

 and thick in turtles. In some lizards fusions occur at the 

 midline in the posterior region of the kidneys. The surface 

 of the kidney may be strongly lobate, ridged, or folded with 

 wrinkles. The kidney is drained by a ureter which may ex- 

 tend along the entire structure and continue posteriorly to 

 its entrance into the cloaca, as in the snake, or it may be 

 very short, arising at the middle of the kidney and extend- 

 ing posteromedially to the cloaca, as in some lizards. The 



epididymis 



bladdi 



cloaca! 



mesentery supporting gut 



epididymis 



mesentery of gut. 



marginal canal of testis 



kidney. 



genital pore 

 cretory pore 



testis supported by 

 mesorchium 



genitoinguinal ligament 



.vas deferens 



urinary pore 

 genital pore 



opening for aversion of hemipenis 



, , ' ■ I ', ^>— hemipenal sac 



I ', I ' ' I ,' ) 



VARANUS 



***.=&*«?<;;* 



vas deferens and papilla 



bladder 



opening of gut info cloaca 



SPHENODON 



TURTLE 



Figure 1 0-8. Urogenital systems of reptiles. A, ventral view of Sphenodon; B, of Voranus; C, of a 

 turtle (Te.'jtudo). (After van den Broek 1933, 1938) 



296 



THE UROGENITAL SYSTEM 



