THE PITUITARY BODY 



concluded from a study of the ovaries of the injected rats and 

 from implantation experiments that the effects of oestrin on 

 the production of gonadotropic hormone(s) by the pituitary 

 occurred in two stages. The early effect was an increased 

 liberation of gonadotropic hormone(s). This was soon fol- 

 lowed by a stage of diminished liberation and secretion of the 

 follicle-stimulating hormone. In this later stage there was an 

 increased secretion and liberation of luteinizing hormone 

 shown by the production of numerous "vesicular follicles." 



Kuschinsky (193 1) reported that the injection of 25 rat- 

 units of prolan daily for 10 days to adult female rats caused a 

 reduction in the amount of gonadotropic hormone in the 

 pituitary. This appeared to be due to the inhibitory effect of 

 ovarian hormone(s) liberated in increased amounts, for the 

 effect was not observed in spayed rats. Goodman (1934), by 

 injecting oestrin, caused a partial or complete atrophy of suc- 

 cessful transplants of the ovary in the anterior chamber of the 

 eye of rats. Presumably the oestrin inhibited the secretion of 

 gonadotropic hormone essential for the maintenance of the 

 transplant. 



A curious observation was made by Emery (1933). He re- 

 ported that immature rats were abnormally refractory to 

 oestrone for several weeks after precocious sexual maturity 

 had been produced either by implants or by extracts of the 

 anterior pituitary. As much as 100 rat-units of oestrone 

 ("Theehn") did not produce oestrus. Neither ovariectomy 

 nor hysterectomy made the rats less refractory. 



The internal secretion of the corpus luteum in relation to the 

 secretion oj gonadotropic hormone{s) by the anterior pituitary. — 

 There is not much direct evidence that the administration of 

 corpus luteum hormone (progesterone) affects the secretion 

 of gonadotropic hormone. According to Hohlweg and Dohrn 

 (1931), the anatomical changes in the pituitary characteristic 

 of castration in the adult spayed female rat can be prevented 

 by the daily injection of i rat-unit of oestrin and \ rabbit-unit 



[154] 



