248 



NORTH AMERICAN FAUNA 68 



The material examined appeared to indicate quite strongly that there was 

 such a periodicity. All adult animals showed a germinal epithelium in a 

 state of active production of germ cells, but not all showed an appreciable 

 number of late stages of spermatogenesis. No animal indicated as "old," 

 [animals having well-worn teeth were arbitrarily classified in the field as 

 old] showed any signs of diminished sperm output ; in fact, all of these animals 

 (3) showed many late stages of spermatogenesis. 



Two cases (62-92 and 62-228) were probably hypotrophic. Both were poorly 

 preserved (hypotrophic testicles are commonly more difficult to preserve 

 well). It appeared to me that these two cases are possibly significant. They 

 may indicate either a fairly high percentage of males with degenerative test- 

 icles and consequently low fertility, or they may indicate a periodicity in the 

 spermatogenic activity which would appear more pronounced when specimens 

 taken throughout the year are investigated. Both hypotrophic testicles showed 

 hypotrophic Leydig cells. 



The Leydig cells of the normal, adult sea otter testis appear to be ag- 

 gregated in huge masses around the rete channels and almost form an 

 "endocrine organ" in this location. From there, long strands of these cells 

 penetrate into the septa, usually in very close apposition to thin-walled veins. 

 The rete itself is fortified very strongly with a coarse network of collagenous 

 fibers. The general structure of the seminiferous tubules is entirely typical 

 for mammals. 



One conclusion that appears justified on the basis of the testes 

 examined is that the production of spermatozoa in the sea otter 

 exhibits a mild or modified periodicity. There is no indication 

 that a distinct seasonal periodicity in sperm production exists, as 

 in many distinctly seasonal breeders, or that there is continuous 

 production of sperm as in the rat. A comprehensive study of 

 reproduction in the male sea otter remains to be done. 



