498 THE REPRODUCTIVE SYSTEM 



a single, sometimes a multiple cell layer. They possess spherical or 

 ovoid nuclei which lie in their deepest third. Their cytoplasm is finely 

 granular and often contains small yellowish granules. The epithelium 

 rests upon a prominent membrana propria, composed of peculiar coarse 

 collagenous fibers, 'B-collagenous' fibers (Ferguson, Anat. Rec., 5, 12, 

 1911) somewhat resembling, but not identical with, reticulum. This 



FIG. 441. SEVERAL ALVEOLI OF THE HUMAN PROSTATE GLAND, SEEN IN SECTION. 

 Hematein and eosin. Photo. X 160. 



type of fiber is present also throughout the stroma and distinguish- 

 able by the Bielschowsky technic from the usual collagenous ('A-col- 

 lagenous') fibers. 



The epithelium is remarkably folded upon itself, the narrow interval 

 between the two layers of the epithelial folds being always occupied by 

 delicate extensions of the connective tissue stroma. The prominence 

 of the folds varies greatly in different tubules, some showing scarcely 



