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.

The secretion of bioactive and immunoreactive follicle-stimulating hormone (FSH) and luteinizing hormone (LH) throughout the menstrual cycle of the rhesus monkey (Macaca mulatta).

The present study provides the first evaluation of related changes in serum levels of bioactive FSH (Bio FSH) and immunoreactive FSH (iFSH), and concurrent dynamics of LH and FSH bioactivity throughout the menstrual cycle of the rhesus monkey. Mean concentrations of Bio FSH were elevated on days 0 and 1 (n = 7; P < 0.05; day 0 = preovulatory LH surge).

Estradiol-induced follicular atresia in rhesus monkeys is not prevented by exogenous gonadotropins.

Estradiol-17β (E) induces atresia of the dominant preovulatory follicle (DF) when administered on day 6 of the menstrual cycle. The present study was designed to determine whether the atretogenic effect of E could be averted by the administration of exogenous gonadotropins, in an attempt to determine whether E-induced atresia in primates is due to a direct action at the ovarian level or is mediated via pituitary secretion. After identification of the DF during laparoscopy, cyclic monkeys received Silastic capsules containing E placed s.

Direct effect of estradiol-17β on progesterone accumulation by ovarian granulosa cells from rhesus monkeys.

We have previously demonstrated that estradiol-17β (E) administered in vivo induces atresia of the dominant ovarian follicle (DF). Whether this effect is exerted directly at the ovarian level or by central mediation has not been confirmed. The present study was designed to assess whether E in amounts similar to those found in monkey follicular fluid (FF) directly alters in vitro progesterone (P) accumulation by granulosa cells (GC) aspirated from follicles in cycling rhesus monkeys.

Atresia of the dominant ovarian follicle in rhesus monkeys is detected within 24 hours of estradiol treatment.

Following treatment with estradiol-17β (E) on day 6 of the menstrual cycle, degenerative alterations in the microenvironment of the dominant follicle (DF) (follicular fluid [FF], granulosa cells [GC], and oocyte) are readily apparent on day 10, or 96 h after E administration. The present study was designed to determine how early such changes could be detected and which indices of atresia were observed first. The DF was identified during laparoscopy on day 5 or 6 of the cycle, and four capsules containing crystalline E were inserted s.

Induction of atresia of the dominant follicle in rhesus monkeys (Macaca mulatta) by the local application of estradiol-17β.

Estradiol-17β (E), administered systemically to rhesus monkeys during the follicular phase of the menstrual cycle, induces atretic changes in the microenvironment of the dominant follicle (DF), which results in its demise. It has been proposed that this effect of E represents a direct action at the ovarian level. The present study was designed to test this hypothesis, using local treatment with E.

Menstrual cycles in rhesus monkeys (Macaca mulatta) are unaffected by a single dose of the anesthetics ketamine and xylazine administered during the midfollicular phase at laparoscopy.

To identify an anesthetic regimen that produces more complete relaxation and analgesia than ketamine hydrochloride (Ketaset®) alone, a combination of ketamine (15 mg/kg body weight) and the hypnotic xylazine (Rompun®, 0.33 mg/kg) was evaluated. Since the desired experimental application required that the anesthetic not interfere with normal hormonal events during the menstrual cycle, this combination administered on day 6 of the cycle was tested to determine whether hormonal surges, incidence of ovulation, or cycle length would be altered relative to the use of ketamine alone.

Atretogenic action of estrogen in rhesus monkeys: Effects of repeated treatment.

The effects of 17β-estradiol (E), administered in Silastic capsules for 24 hours at intervals of 10 or 14 days, on follicular development and menstrual cycle characteristics were studied in 13 rhesus monkeys. In seven monkeys receiving E at l0-day intervals for 50 treatment periods, new follicles frequently developed between treatments but usually regressed. In seven instances, the follicles persisted longer than expected but were steroidogenically suppressed and regressed spontaneously.

Temporal and endocrine sequelae of aspirating follicular contents in rhesus monkeys.

Aspiration of ovarian follicular contents in humans is a well-established procedure used to obtain oocytes for fertilization in vitro (IVF). However, the effects of aspiration on the menstrual cycle and resulting luteal function have been incompletely characterized. The present study was designed to investigate alterations in the temporal and endocrine characteristics of menstrual cycles following aspiration of contents of the dominant preovulatory follicle (DF) on day 10 of the cycle in normal rhesus monkeys.

Excessive ovarian follicular development in pregnant pigtailed macaques (Macaca nemestrina).

To evaluate the status and possible control of ovarian follicular development during pregnancy, circulating levels of estrone (E), estradiol-17β (E), and follicle-stimulating hormone (FSH) were measured throughout gestation in both intact and ovariectomized pregnant pigtailed monkeys (Macaca nemestrina). From an additional group of pregnant monkeys, ovaries were obtained at late gestation (on day 150 or 159 of pregnancy) for histological studies. Circulating concentrations of E and E increased on day 13 and remained elevated for about 10 days; they then declined and reached low levels on day 32 of gestation.