HORMONE SECRETION BY THE IMMATURE MOUSE OVARY AFTER GONADOTROPHIC STIMULATION

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Abstract
Pregnant mare serum gonadotropin was given in single subcutaneous injections to mice 21 days old. The dose level ranged from 340 [mu]g (17.7 C.N.U.) down to 0.07 [mu]g (0.004 C.N.U.). Above a level of 1,1 [mu]g corpora lutea formed; from that level and down to the minimal effective dose the ovary did not respond by weight increase or morphological change. However, the ovary did respond physiologically at the subluteinizing levels as evidenced by marked uterine weight increase and morphological changes. At all dose levels, including the subluteinizing levels, there were changes in the endometrium indicative of the presence of both progestin and estrogen. Another series of mice were given single subcutaneous injections of a subluteinizing dose of the same gonadotropic preparation (1.1 [mu]g or 0.06 C.N.U.) and sacrificed 12, 24, 36, 48, 60, 72, and 120 hours later. There was no distinct change in ovarian morphology. However, there was an increase in uterine weight. Endometrial morphology indicated that progestin was present throughout the experiment. Only a slight indication of an estrogen response was present at 12 hours postinjection; the response increased until 60 hours and then declined. It appears that estrogen and progestin were secreted simultaneously in response to the gonadotropin. A luteinizing dose of this preparation had no effect on uterine morphology of ovariectomized mice, ruling out the possibility of adrenal participation.