THE GONADOTROPIC HORMONES 



gonadectomized partner's anterior pituitary. Large cystic 

 ovaries are developed — a phenomenon which apparently pro- 

 ceeds indefinitely (e.g., 15 months). In response to this en- 

 dogenous gonadotropic hormone formed in great excess there 

 is no compensatory production of antihormone (see Fig. 16). 

 Finally, it must be realized that potent gonadotropic prepa- 

 rations, although administered for a prolonged period, do not 

 necessarily bring about refractoriness of the "end-organ" 

 (e.g., the ovary) with atrophy as is so commonly the case. 

 Katzman, Wade, and Doisy (19,37) inserted homo-implants 

 of the pituitary into female rats for 210-75 days. At the end 

 of the period of treatment the ovaries still were enlarged, and 

 there was no gonadotropic (or thyrotropic) antihormone in 

 the blood. ■'^ Fluhmann (1936) observed that a gonadotropic 

 extract of the blood of pregnant women still maintained a 

 marked ovarian hypertrophy in rats receiving injections for 

 as long as a year," In Thompson's experiments (1937) sheep 

 received, for six months, injections of a sheep pituitary ex- 

 tract which readily produced gonadotropic antihormone in 

 other species of animals. Yet none could be clearly detected in 

 the blood of the sheep. 



2. The inhibition of go?jadotropic effects by substances other 

 than antihormone s J'' — Extracts of the pituitary body may, 

 under suitable conditions, antagonize the action of gonado- 

 tropic substances such as prolan, pregnant-mare serum, and 

 gonadotropic pituitary extract. To this hypothetical sub- 

 stance Evans has given the name "pituitary antagonist." 

 Its inhibition of gonadotropic effect is most characteristically 

 manifested when administration is intraperitoneal. Evans 

 and others (1936) have described methods of preparing the 

 substance free from follicle-stimulating or luteinizing effects. 



'^ There was no significant alteration in the weight of the adrenals, thyroid, or 

 pituitary (see also the similar experiments of Artemov, 1937). 



7^ The ovaries contained large corpora lutea, lutein cysts, and developing follicles. 

 There was hypertrophy of the pituitary with associated histologic changes. 



'^ See also the effects of lactogenic extracts (pp. 98-99). 



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