Abstract
Studies of female rats united parabiotically with castrated males have shown that they are characterized by constant estrus and that their ovaries contain only large follicles (Witschi and others). The phenomenon appears to establish the actual secretion into the blood stream of the follicle stimulating hormone only on the part of the pituitary of the castrated male parabiont. The present study shows that the pituitaries of such castrated males nevertheless contain or “house” appreciable amounts of luteinizing hormone.
Young mature males were castrated and after 40 days their pituitaries were implanted into hypophysectomized females 26 days of age. While a dose level was found in which follicles only occurred in the ovaries of the hypophysectomized recipients, double this dose (4 glands) led to the appearance of corpora lutea. Implants of the hypophyses from normal litter brothers produced only follicles at both dose levels. Parallel experiments with normal recipients showed that corpora were produced by both levels of castrate and normal hypophyses.
The luteinizing effect of castrate male hypophysis as tested by implantation, therefore, contrasts with the results obtained by parabiosis. The explanation offered for the difference is that the absorption of the implant frees the factor responsible for luteinization, whereas this substance is retained in vivo by the hypophysis of the parabiont.
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