MALE OEGANS OF REPRODUCTION 



487 



it is uncertain whether they can maintain their functional virility for 

 this length of time. The number of spermatozoa per cubic millimeter 

 has been estimated at 60,87(5 ; and the total in 

 an average ejaculation at 200,000,000 (Lode, 

 1896). 



The tubuii convoluti pass into short tubuli 

 recti and the latter into the rete testis of the 

 mediastinum. The rete testis is the beginning 

 of the excretory duct, and consist of a meshwork 

 of irregular tubules lined with a single layered 

 cuboid non-ciliated epithelium. They connect 

 with a group of greatly coiled tubules, the duc- 

 tuli efferentes, from ten to fifteen in number, 

 each terminally winding so as to assume a coni- 

 cal shape, hence coni vasculosi which tubules 

 empty into the distal portion of a common duct 

 the ductus epididymis. This portion of the 

 duct, together with the efferent ductuli, consti- 

 tute the globus major of the epididymis. Con- 

 sideration of the duct system will follow below. 

 Interstitial Cells of Leydig. Here should 

 be considered the intertubular connective tissue 

 of the testis. Fibro-elastic connective tissue acts 

 as a supporting stroma for the testicular paren- 

 chyma of the seminiferous tubules. Scattered 

 throughout this stroma, between the adjacent 

 tubules, are peculiar large polygonal cells, inter- 

 stitial calls of Leydig, either scattered or ar- 

 ranged in masses. The condition of the nucleus 

 varies from pale vesicular to dense deeply chro- 

 matic. Division figures are exceedingly rare 



among them, though an occasional cell may, in young testes, be seen in 

 mitosis. In older testes an occasional nucleus may be seen in what 

 appears to be amitotic division. A number of the cells also are hi- and 

 multinucleate. However, multiplication of specific interstitial cells is 

 evidently exceptional. These cells arise directly through modification in 

 shape, and growth from the fusiform and irregular connective tissue 

 cells of the stroma. Moreover, this process seems to be reversible. They 

 thus represent a transient phase in the life of certain cells of the inter- 

 tubular connective tissue. Their cytoplasm contains crystalloids (rnito- 

 31 



FIG. 432. SPERMATO- 

 ZOA FROM THE SEMEN 

 OP MAN. 



A, usual type; B, 

 'giant' double sperma- 

 tozoon. Hematein and 

 eosin. X 1200. 



