Necturus Testis and Reproduction 65 



* 1 





W 



Fig. 9. The "epithelioid ring" of hypertrophied Leydig cells (arrows) surround- 

 ing the degenerating lobules (arrowheads). X 330. 



STEROID PRODUCTION BY NECTURUS TESTIS 



We became interested in Necturus when it was demonstrated that 

 the testes of N. maculosus possessed exceptionally high aromatase activ- 

 ity when homogenates of this tissue were incubated with a steroid pre- 

 cursor [ 3 H]-androstenedione (Callard et al. 1978). Although it has long 

 been recognized that estrogens can be synthesized and secreted by the 

 testis of many species, the exact intratesticualr site of aromatization is 

 still controversial. Thus, both interstitial Leydig cells and intertubular 

 Sertoli cells have been implicated as the source of testicular estrogens. 

 Since the previous study had demonstrated such high aromatase activity 

 in the testes of Necturus, we thought they would be convenient animal 

 models to study the specific site of estrogen production. 



The formation of the peripheral glandular tissue at the end of the 

 breeding season results in a distinct zonation of Necturus testis, which 

 can be readily visualized with the aid of a dissecting microscope (Cal- 

 lard et al. 1980). Hence, the testes can be easily dissected into the glan- 

 dular tissue, which is composed mostly of fully differentiated Leydig 

 cells and another component comprised of seminiferous lobules contain- 

 ing immature germ cells and their associated somatic cells. This fortui- 



