THE GONADOTROPIC HORMONES 



if injected during midpregnancy or late pregnancy. Oestrone 

 caused the same effect in 0.003 the dose (or less) of androgen 

 required. Recently, Moore and Price (1937) studied the 

 effect of androsterone on the testes and on the gonadotropic 

 potency of the pituitary of young rats. The daily injection of 

 0.5-1.5 mg. of the androgen for 20 days inhibited testicular 

 growth 12-50 per cent and reduced the gonadotropic action 

 of the injected rat's pituitary. There was no stimulation of 

 spermatogenesis. The authors concluded that the testicular 

 damage was the indirect result of pituitary injury. On the 

 other hand, enormous doses of androsterone (4-6 mg. daily 

 for 20 days) appeared not to affect the testes of adult rats. 



It will be recalled that the gonadotropic potency of pitui- 

 tary implants increases after gonadectomy. Therefore, the 

 normal internal secretions of the ovary or testis appear to in- 

 hibit the secretion (storage) of gonadotropic hormone. Clark 

 had earher found that, judged by the gonad-stimulating 

 effect of pituitary implants, secretion of testicular hormone 

 occurs much earlier than secretion of ovarian hormone in the 

 rat. In other words, castration at an early age is followed by 

 an increased gonadotropic effect of the pituitary, whereas 

 spaying produces no change. Stein (1935) has shown by this 

 technic that there is considerable testicular secretion even in 

 the first week of the male rat's life. A confusing exception to 

 the generalization that gonadectomy is followed by increased 

 storage or secretion of gonadotropic hormone is that reported 

 by Bates, Riddle, and Lahr (1935). They found that the 

 concentration of gonadotropic hormone in the pituitary of the 

 ox, as indicated by testicular hypertrophy in immature doves, 

 is lowest in the castrated animal (adult steer), apparently 

 being lower than in the pituitary of the bull, calf, embryo, 

 etc. 



Another aspect of the problem which can be interpreted as 

 indicating an inhibiting effect of androgens on pituitary 

 gonadotropic function is the prevention or correction of cas- 

 tration changes in the pars glandularis. This has been ac- 



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