THE GONADOTROPIC HORMONES 



mammals. — In normal male mammals, the typical effects of 

 prolan — best observed in immature specimens — are on the 

 interstitial cells of the testis (cells of Leydig). These secrete 

 "male hormone," which is probably testosterone, at a more 

 rapid rate so that the secondary sexual organs, such as the 

 epididymides, seminal vesicles, and prostate, undergo ab- 

 normal hypertrophy and, histologically, may resemble the 

 organs of adult animals. Such changes, of course, are absent, 

 if the prolan-sensitive cells have been removed by castra- 

 tion. In immature mammals prolan does not initiate sperma- 

 togenesis. In adult animals, however, prolan, if administered 

 immediately after operation, will maintain spermatogenesis 

 after hypophysectomy (Smith and Leonard). This probably 

 is due to the fact that the secretion of androgenic hormone 

 by the interstitial cells continues as a result of the injec- 

 tion of prolan. It is well known that androgens by them- 

 selves may have this effect (see chap. iii). This fact probably 

 accounts for the spermatogenesis which may be initiated in 

 the ground squirrel {Citellus tridecemlineatus) by the injection 

 of prolan at times of seasonal involution of the gonads (Baker 

 and Johnson, 1936; Wells and Moore, 1936). 



Other reports not reviewed previously are those of van Os 

 (1936) and Kuschinsky and Tang (1936). Van Os could not 

 bring about spermatogenesis in the testes of rats in which 

 testicular degeneration had followed vitamin-A deficiency or 

 cryptorchidism, Kuschinsky and Tang stated that the typi- 

 cal effects of prolan (seminal-vesticle hypertrophy, no con- 

 sistent effect on testicular weight) could be observed in rats 

 receiving prolan when only 6-13 days old. 



1. Female mammals. — In female mammals the most strik- 

 ing effect of prolan is on the cells of the corpus luteum or 

 on the cells of the theca interna — parent cells of corpora 

 lutea. It may appear that follicle growth is stimulated, and 

 some authors believe that prolan is composed of an "A" 

 component, stimulating the follicle, and a "B" component, 

 causing luteinization. Good evidence that both components 



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