Endocrine and ultrasound evaluation of the response to PGF 2alpha and GnRH given at different stages of the luteal phase in cyclic ewes.

To investigate the effects of prostaglandin (PGF 2alpha) plus GnRH at different stages of the luteal phase 13 ewes received PGF 2alpha on Day 9 of the synchronized cycle, followed 36 h later by GnRH. This control regimen resulted in ovulation and normal corpus luteum (CL) function. In the next cycle, the ewes were treated simultaneously with PGF 2alpha and GnRH either on Day 4 (early, n = 7) or Day 9 (late, n = 6).

Role and site of estrogen action in follicular atresia.

Subsequent to an initial understanding that estrogen was only stimulatory to folliculogenesis, we have come full circle to the present recognition that many actions of estrogen are inhibitory to follicular function. The development of this interpretation has frequently been associated with the controversial issue o f the likely site o f estrogen action, especially in primates, where much of the evidence has been amassed. The accumulated findings in a variety of species seem to demonstrate clearly that at least part of the atretogenic effect of estrogen is exerted directly on the ovary, apparently by interaction with the nuclear estrogen receptor.

Incidence of atresia or of luteinization without rupture of the dominant ovarian follicle in rhesus monkeys treated with estradiol-17β on day 8 of the menstrual cycle.

Previous results have established that 17β-estradiol (E) administered in capsules for 24 h on Day 6 of the menstrual cycle results in atresia of the dominant follicle (DF). The present experiment was designed to determine if atresia could be induced similarly as late as Day 8, when the DF is presumably larger, to facilitate biochemical analyses. On the morning of Day 8, laparoscopy was used to confirm the presence of the DF, and 4, 6, or 8 Silastic capsules containing E were placed s.

Non-surgical uterine flushing for the recovery of preimplantation embryos in rhesus monkeys: Lack of seasonal infertility.

A non-surgical uterine flushing technique was employed to recover rhesus monkey preimplantation embryos during April--September, a period thought to be associated with reduced fertility. A total of 22 females of proven fertility, maintained indoors under strict light and temperature control, were employed for the study in which 72 menstrual cycles were monitored. The average length of their menstrual cycle was 27.

Localization of estrogen receptors in rhesus monkey ovary.

We have previously demonstrated that the exogenous administration of estradiol-17β (E) to rhesus monkeys induces atresia of the dominant preovulatory follicle (DF); and that this effect is mediated centrally, via the inhibition of follicle-stimulating hormone, and is also exerted directly at the level of the ovarian granulosa cell. We wished to investigate whether the local effect of E is transduced through interaction with the nuclear receptor for estrogen, particularly in light of certain evidence that suggests a general lack of estrogen receptor (E-R) in the rhesus monkey ovary, except in the germinal epithelium. In the present study, we evaluated the presence of E-R by both autoradiographic and immunocytochemical techniques.