814 THE MALE GENITAL TEACT. 



color resembling tubular epithelia. Their significance is not 

 understood. (See Fig. 369.) 



The seminiferous tubules show three marked divisions, which 

 are: the convoluted, the straight portion, and the rete testis. The 

 convoluted tubules compose the main mass of the testis, and at 

 the periphery unite and form a continuous closed net- work having 

 a few offshoots with blind terminations (Mihalkovics.) By con- 

 tinuous union at acute angles their number decreases toward the 

 corpus Highmori ; they gradually become less convoluted, and 

 continue until, with an abrupt narrowing, they pass into the 

 straight portion. The caliber of the straight tubules is about 

 one-third the size of the convoluted. These tubules are imbedded 

 in a broad connective-tissue layer, and inosculate with the rete 

 testis, which forms a dense, narrow, and sinuous net- work of 

 tubules, occupying the spaces of the corpus Highmori. From 

 this net- work arise the efferent vessels of the epididymis. 



The convoluted tubules have a lining of irregular cuboidal 

 epithelia, arranged in several layers. The outermost layer is, as 

 a rule, composed of coarsely granular elements, while the inner 

 layers are in the condition of rest, either uniformly distributed 

 or arranged in rows irregularly projecting toward the central 

 caliber. In the condition of rest the caliber is found either 

 empty or filled with an albuminous liquid, which, in specimens 

 hardened in chromic acid, appears finely granular. In some 

 tubules no trace of spermatozoids can be discerned ; in others, 

 especially in men who have died of chronic wasting diseases, 

 the spermatozoids are scanty; other tubules, on the contrary, 

 are entirely filled with epithelia, and their offspring the sper- 

 matozoids. In the rat's testis, and in all animals during the 

 rutting period, the spermatozoids are in most portions of the 

 convoluted tubules so numerous that their tails fill the central 

 caliber, showing a spiral, sheave-like arrangement. (See Fig. 

 370.) 



The connective-tissue layer next to the epithelia (the mem- 

 brana propria) is composed of a number of delicate strata, 

 which, according to Mihalkovics, are composed of a number of 

 closely packed, flat endotholia, their nuclei being traceable in a 

 more or less homogeneous, elastic basis-substance. 



Regarding the formation of spermatozoids, the views of in- 

 vestigators differ widely ; some claiming that only certain 

 epithelia, the so-called spermatoblasts, participate in the forma- 

 tion of the spermatozoids, while other epithelia produce mucus 



