492 



V. D. LESPINASSE 



may be observed in sections of the testis. When isolated, these tubules 

 are seen to begin in the testis as closed canals, which are closely coiled upon 

 each other (convoluted tubules) and describe a tortuous course, until they 

 finally reach the corpus Highmori. 



The epithelium of the convoluted seminiferous tubules consists of sus- 

 tentacular cells (cells or columns of Sertoli) and of spermatogenic 

 elements. The former are high, cylindric structures, the basilar surfaces 

 of which are in contact. They do not form a continuous layer, but their 

 basal processes are interwoven to form a superficial network surrounding 



the epithelium of the seminifer- 



of the normal 



ous tubules. In the meshes of 

 the reticulum are deposited 

 numbers of plate-like cells, 

 which lie in contact with the 

 basement membrane and also 

 represent sustentacular ele- 

 ments. 



Between the sustentacular 

 cells are found from four to six 

 rows of cells, possessing rela- 

 tively large nuclei, rich in chro- 

 matin, and derived from cells 

 of the deeper strata by mitotic 

 cell division. The epithelium 

 of the convoluted portion of the 

 seminiferous tubules is, there- 

 fore, a stratified epithelium. 

 The cells of this epithelium pre- 

 sent various peculiarities according to their stage of development, and will 

 not be considered more fully as they have to do with spermatogenesis. 

 Externally, the walls of the convoluted tubules are limited by a single layer 

 or several layers of spindle-shaped, epithelioid cells. A basement mem- 

 brane is present, but very thin, and in some cases hardly capable of dem- 

 onstration. The convoluted tubules are separated from each other by a 

 small amount of connective tissue, in which, in addition to the vessels, 

 nerves, etc., are found peculiar groups of large cells containing large 

 nuclei, and known as interstitial cells. 



Interstitial cells as seen in a section of the adult testicle appear as 

 a more or less isolated collection of cells lying in the irregular triangular 

 interval between the sections of the seminal tubules. These cells are ir- 

 regularly quadrangle arid are usually molded to fit the irregular space in 

 which they lie. They send out projections which undoubtedly pass be- 

 tween the spermatogenic tubules and anastomose with the projections of 

 the other interstitial cell masses. They are also found between the tubuli 



Fig. 1. Photomicrograph 

 testicle of a dog. 



