THE GONADOTROPIC HORMONES 



carried as far as the secondary spermatocyte stage. The lu- 

 teinizing extract brought about growth of the interstitial tis- 

 sue but left the germinal epithelium as "degenerate" as in 

 control animals. Increased diameter of the tubules in rats 

 receiving luteinizing extract was believed to be the result of 

 generalized swelling of the tubules partly owing to the accu- 

 mulation of fluid in the lumen. The administration of a mix- 

 ture of the two extracts apparently produced an augmented 

 effect on the secondary organs. The general results are in 

 agreement with the views of many authors: a pituitary folli- 

 cle-stimulating hormone maintains gametogenesis in the male; 

 a pituitary luteinizing hormone is essential for the normal 

 functioning of the interstitial tissue. However, proof to si- 

 lence all arguments to the contrary awaits the isolation of the 

 hormones in pure form. 



Pfeiffer (1936-37) offered experimental evidence that the 

 pituitary of the male rat secretes only follicle-stimulating 

 hormone, whereas the female pituitary secretes both follicle- 

 stimulating and luteinizing hormone. His conclusions are 

 supported by a different type of data — i.e., effects of extracts 

 or implants of the pituitaries of male or female rats — gath- 

 ered by others. Thus it would appear that follicle-stimulat- 

 ing hormone alone maintains both the germinal epithelium 

 and the interstitial cells of the testis of the normal rat. Greep 

 has suggested that minute continuous secretion of luteinizing 

 hormone (the male rat's pituitary does contain a very small 

 amount of this hormone) by the male pituitary may be suffi- 

 cient for the needs of the interstitial cells, which probably 

 secrete continuously rather than in a cyclic fashion. The 

 cyclic course of ovarian activity as well as the action of 

 oestrogen on the pituitary might account for the much larger 

 amount of luteinizing hormone secreted by the female pitui- 

 tary. A later report of Greep and Fevold (1937) further com- 

 plicates discussion. Follicle-stimulating hormone or luteiniz- 

 ing hormone was administered to adult hypophysectomized 

 male rats. Spermatogenesis could be maintained by either 



[75] 



