PHYSIOLOGY, CHEMISTRY AND PATHOLOGY 447 



The interstitial cells sustain an intimate relationship with the rich 

 capillary mesh work of the testis; they surround the capillaries in their 

 course to the seminal tubules, and are bathed in the large intertubular 

 lymph spaces. Hence, the morphological position of the interstitial cells 

 suggests the possibility of an intimate relation with the body fluids or 

 distributors of internal secretions. Further, as spermatogenesis proceeds 

 in the normally functioning testis, the large fat droplets present in the 

 basal portion of the sustentacular cells divide into smaller portions, pass 

 centralward into the prolongations of the cells and then on into the 



Fig. 8. The urogenital organs of a monocryptorchid pig (the other testicle had 

 descended normally and had been removed). (Hanes, 1011, Plate XXTV, Fig. 9.) 



The three photographs are taken to scale and show the bladder, prostate, seminal 

 vesicles, glands of Cowper, and penis. The organs of the castrated pig (Fig. 9) are 

 small and atrophic, whereas the organs of the cryptorchid pig (Fig. 11) are as well 

 developed as in the normal animal (Fig. 10). 



spermatids (Hanes). During this migration the neutral fat changes to a 

 lipoid. Spermatogenesis is absent in the cryptorchid testis, hence, if the 

 function of the sustentacular cells is to transmit nourishment to the 

 spermatids, the absence of spermatkls from the seminal tubules should 

 result in the accumulation of fat in the sustentacular cells. Histological 

 preparations of cryptorchid testis stained to show fat demonstrate that 

 the sustentacular cells are loaded with fat droplets. Chemical analyses 

 of cryptorchid and normal testes further confirm this view. The fat 

 content of the dried weight of normal pig testes, according to Hanes 

 and Eosenbloom, is 19 per cent, while that of cryptorchid testes is 31 

 per cent. Hence it may be concluded that fat accumulates in the sus- 

 tentacular cells of the cryptorchid testis because of the absence of sper- 

 matogenic cells which normally utilize this substance. 



