THE UROGENITAL SYSTEM 87 



caiida epididymidis behind. The latter expands posteriorly 

 and curves down around the posterior end of the testis. 

 The ductus deferens is the conspicuous tube which passes 

 forward from the median side of the cauda epididymidis, 

 through the inguinal canal into the abdominal cavity. 



The epididymis and ductus deferens are both attached to 

 a mesentery which extends from the dorsal side of the testis 

 to the dorsal wall of the scrotal cavity. Anteriorly this 

 mesentery also incloses the blood vessels which carry blood 

 to and away from the testis. Fat accumulates in consider- 

 able quantity in front of the epididymis and within ventral 

 prolongations of the mesentery which extend through the 

 inguinal canal into the abdominal cavity. 



The mammalian scrotal cavity, like the abdominal cavity 

 from which it is derived, is lined with peritoneum, the 

 tunica vaginalis. The testis, like the intestine, is almost 

 completely invested with peritoneum and is suspended 

 in the scrotal cavity by the mesentery, which is covered on 

 both sides by the peritoneal layer. The wall of the testis 

 is a very tough, fibrous, transparent membrane, the tunica 

 alhitginea. This incloses a mass of convoluted seminiferous 

 tubuleSy readily seen through the tunic. Slit the latter 

 lengthwise of the testis and with a needle tease out some 

 of the tubules, noting their convolutions. These tubules 

 produce the spermatozoa. 



The epididymis is covered by a tough transparent mem- 

 brane similar to the tunica albuginea of the testis. Through 

 the membrane may be seen tubular convolutions. The 

 ductus deferens becomes coiled when it enters the cauda 

 epididymidis. Verify this by a careful dissection. 



In man the spermatozoa, prodilced by the epithelial lin- 

 ing of the seminiferous tubules, pass through efferent ducts, 

 the ductuli efferentes testis, to the caput epididymidis, 

 where they are collected into a single duct, the duct of the 



