Proestrous hormone surges dissociated from ovulation in the estrogen-treated hamster.

Endocrinology
G S Greenwald

Abstract

Hamsters injected sc with 50 mug estradiol cyclopentylpropionate (ECP) at 0900 h on day 1 (metestrus) of the cycle show the normal "postovulatory" vaginal discharge 4 days later but do not resume ovulation until 14--18 days later. After ECP injection ovarian histology reveals that the follicles normally destined to ovulate at the end of the cycle (developing follicles) are healthy on the afternoon of day 1, but atretic by day 2. Developing follicles (8--12 granulosal layers) reappear by the afternoon of day 3; follicular development is still retarded by the afternoon of proestrus (day 4). Serum hormone levels were determined by RIA in ECP and oil treated hamsters. ECP fails to affect the normally high levels of FSH present throughout day 1; however, by day 2 both FSH and LH levels are usually undetectable. On day 3, a "rebound" phenomenon occurs and FSH and LH are now detectable in the ECP treated groups. The preovulatory increase of LH occurs on day 4 between 1200 and 1400 h in both groups whereas FSH increases at 1400 h in the ECP group but not until 1600 h in the controls. The elevated levels of FSH, usually observed throughout day 1, occur in the oil treated but not in the ECP group. This most likely accounts for the long d...Continue Reading

Citations

Jun 1, 1987·Cell and Tissue Research·R J HutzD J Dierschke

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