The Testis and Reproduction in Male Necturus, 

 with Emphasis on N. lewisi (Brimley) 



Jeffrey pudney 



Department of Biology, Boston University 



Jacob A. Canick 



Brown University, 



Division of Biology and Medicine 



Department of Pathology 



Women 's and Infants ' Hospital 



Providence, Rhode Island 02908 



AND 



Gloria V. Callard 



Department of Biology 



Boston University, Boston, Massachusetts 02215 



ABSTRACT. — Although it has long been recognized that estrogens 

 are produced by the testis of many vertebrate species the intratesticular 

 site of aromatization is still controversial. Both interstitial Leydig and 

 intertubular Sertoli cells have been implicated as the source of testicu- 

 lar estrogen. The mammalian testis is histologically complex with 

 seminiferous tubules uniformly distributed amongst the interstitial 

 tissue throughout the testis, which makes it difficult to localize steroid- 

 ogenic enzymes within the testis. Urodele amphibians, however, at the 

 close of the breeding season develop a specialized region of the testis 

 called the glandular tissue that is essentially composed of Leydig cells 

 and is formed by hypertrophy of the interlobular Leydig cells following 

 spermiation of the seminiferous lobules. This glandular tissue in Nec- 

 turus testis can be visualized with a dissecting microscope and separ- 

 ated from the seminiferous lobules, an anatomical arrangement that 

 provides an opportunity to investigate the intratesticular location of 

 steroidogenic enzymes. In a previous study it was shown that aroma- 

 tase was localized to the glandular tissue in Necturus maculosus testis. 

 Thus in N. maculosus Leydig cells are responsible for the production 

 of testicular estrogens. The testis of Necturus also undergoes a longi- 

 tudinal wave of spermatogenesis. Due to this topographical 

 arrangement it is possible by dissection of the testis to obtain regions 

 with Leydig cells at different stages of differentiation. This was carried 

 out in N. lewisi towards the end of the breeding season at which time 

 the testis was divided into cephalic and caudal regions. The cephalic 

 region contained seminiferous lobules filled with germ cells and undif- 

 ferentiated interlobular Leydig cells. The caudal region contained 

 lobules that had undergone spermiation and the Leydig cells had 

 hypertrophied to form the glandular tissue. Microsomes were prepared 

 from these two regions and key enzymes for estrogen synthesis, 17a- 

 hydroxylase and aromatase were measured. Cytochrome P-450, the 

 catalytic component of these enzymes, was also measured in each 



Brimleyana No. 10:53-74. February 1985. 53 



