CH. LIX.] 



THE TESTIS 



865 



spermatocytes give rise by division to the spermatids which lie next 

 the lumen. The spermatids become imbedded in the inner ends of 

 the nurse cells, where they grow and become converted into 



FIG. 549. A spermatic! largely 

 magnified. 1, nucleus; 2, 

 nucleolus ; 3, chromatoid 

 body ; 4, idiosome ; 5, centro- 

 somes ; 6, commencement of 

 axial filament. (After Meves.) 



FIG. 550. Cells of the 

 interstitial tissue of 

 the testis with crystal- 

 loid bodies. 



spermatozoa. Every spermatid contains a nucleus, and near the 

 nucleus is another structure called an idiosome, containing a number 

 of microsomes. There are also a coloured or chromatoid body whose 

 function is not known, and two centrosomes (see fig. 549). 



The interstitial connective tissue of the testis is loose, and con- 

 tains numerous lymphatic clefts. Lying in it, accompanying the blood- 

 vessels, are strands of polyhedral 

 epithelial cells, of a yellowish colour 

 (interstitial cells), which frequently 

 contain crystalloid bodies (fig. 550). 



The straight tubules consist of 

 basement membrane and lining cubi- 

 cal epithelium only. The tubules of 

 the rete testis are lined by cubical 

 epithelium ; the basement membrane 

 is absent. The vasa efferentia, coni 

 vasculosi, and epididymis are lined 

 by columnar cells, some of which are 

 ciliated, whilst others are devoid of 

 cilia, and probably possess secretory 

 functions. There is a good deal of 

 muscular tissue in their walls. The 

 vas deferens consists of a muscular 

 wall (outer layer longitudinal, middle 



circular, inner longitudinal), lined by a mucous membrane, the 

 inner surface of which is covered by columnar epithelium. 



The vesiculce seminales are outgrowths of the vasa def erentia. Each 



3 i 



-c 



FIG. 551. Erectile tissue of the human penis, 

 a, Fibrous trabeculse with their ordinary 

 capillaries ; b, section of the veoous sinuses ; 

 c, muscular tissue. (Cadiat.) 



