VI. THE UROGENITAL SYSTEM 



In all vertebrates the organs of reproduction and those con- 

 cerned with the elimination of nitrogenous wastes are so closely 

 associated that it is convenient to study them together. Usu- 

 ally part of one system forms also part of the other. 



The following directions apply to mature specimens. In 

 immature animals it is sometimes difhcult to locate all parts 

 of the urogenital system. After dissecting your own specimen 

 exchange with someone who has made a dissection of the oppo- 

 site sex. DO NOT TAKE SOMEONE ELSE'S SPECIMEN 

 WITHOUT THE OWNER'S PERMISSION. 



Urogenital Organs of the Male Shark 



The testes are the large bodies in the anterior part of the body 

 cavity dorsal to the liver. Each is attached to the dorsal body 

 wall by a mesentery, the mesorchium. 



The kidneys are long, slender, brown bodies extending nearly 

 the length of the body cavity along the dorsal wall. The 

 posterior ends are thicker than the anterior and probably func- 

 tion more in excretion. The shark kidney is a mesonephros or 

 Wolffian body. 



Remove the peritoneum from the surface of one kidney; the 

 long convoluted vas deferens or Wolffia7i duct Is now visible on 

 the ventral surface of it. Posteriorly the Wolffian duct straight- 

 ens out and expands to form a seminal vesicle. Anteriorly, small 

 tubules may be seen passing through the mesorchium from the 

 testis and entering the anterior part of the kidney. These are 

 the vasa efferentia^ which join the kidney tubules. The tubules 

 of the kidney then connect with the Wolffian duct. 



At the posterior end of the kidney, near the median line and 

 partly embedded, is the ureter or accessory mesonephric duct. Do 

 not mistake the heavy ligament for this. 



Cut open the cloaca and find the urogenital papilla and the 

 opening of the rectum. Open the urogenital papilla and find an 



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