STEROID-INDUCED BLOCK OF OVARIAN COMPENSATORY HYPERTROPHY IN HEMICASTRATED FEMALE RATS

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Abstract
SUMMARY: Removal of the right ovaries of 160–180 g. rats was followed in 2 weeks by a hypertrophy of 55 % of the left ovary. This postoperative growth was prevented by the administration of various natural and synthetic steroidal hormones, which were compared at daily doses estimated to produce a 100 % block of the hypertrophy. The following steroids, together with approximate ED 100, were studied: oestrone, 17·8 μg.; oestradiol-17β, 20·4 μg.; oestriol, 95·5μg.; norethynodrel, 72·5μg.; progesterone, 3630μg.;testosterone, 436 μg.; norethisterone, 479 μg.; norbolethone, 155 μg. At doses above ED 100 the natural oestrogens and norethynodrel produced a secondary cycle of ovarian growth, whereas the Δ4-3-oxosteroids depressed ovarian size further. Hemicastrated rats had histologically normal ovaries which contained larger numbers of corpora lutea than those of the intact controls. All compounds appeared to increase follicular development at the ED 100 level; the higher doses of the oestrogens and norethynodrel stimulated excessive luteinization, whereas the Δ4-3-oxosteroids inhibited luteal development and produced large vesicular and cystic follicles.