D. T. Baird

Long-term ovarian function in sheep after ovariectomy and transplantation of autografts stored at -196 C

We have previously demonstrated that ovarian function and fertility can be preserved in sheep after castration by autotransplantation of cryopreserved strips of ovarian cortex. In the current experiments we have investigated the long term survival of such grafts by detailed measurements of ovarian function for a period of nearly 2 yr after autotransplantation. After ovariectomy and transplantation of frozen/thawed grafts, the concentrations of FSH and LH rose to castrate levels for about 14 weeks before falling gradually to reach near-normal levels at about 60 weeks. In the breeding season from October 1994 to March 1995, all ewes had 5-10 estrous cycles that were similar in length to those in the 4 control ewes. Luteal function as indicated by the progesterone concentration was identical before and 11 months after transplantation. In contrast, the basal concentrations of FSH and LH were persistently raised throughout the luteal phase, but showed a normal decline during the follicular phase. The concentration of inhibin A in ovarian venous plasma measured at the end of the experiment 22 months after transplantation was significantly lower than that in control ewes (mean +/- SE, 409 +/- 118 vs. 1914 +/- 555 pg/ml; P < 0.004). Transplantation of frozen/thawed ovarian tissue to SCID mice demonstrated that about 28% of primordial follicles survived the procedure. All of the ovaries transplanted into sheep contained large antral follicles and/or cysts, but very few primordial oocytes when recovered at autopsy after 22 months. These results demonstrate that despite a drastic reduction in the total number of primordial follicles, cyclical ovarian function is preserved in sheep after autotransplantation of frozen/thawed ovarian tissue and provide experimental confirmation that such a technique could provide a means of preserving fertility in women undergoing chemo- or radiotherapy for malignant disease.

PULSATILE SECRETION OF LH, FSH, PROLACTIN, OESTRADIOL AND PROGESTERONE DURING THE HUMAN MENSTRUAL CYCLE

The pulsatile secretion of gonadotrophins and ovarian steroids was studied in normal women at different stages of the menstrual cycle. The concentration of LH, FSH, Prolactin (PRL), oestradiol and progesterone were measured in samples of plasma collected every 15 min for 6 h and the frequency and amplitude of each episodic pulse of hormone estimated. Although significant fluctuations occurred in the concentration of each hormone, LH showed the most easily identifiable pulses the frequency of which increased significantly from the early follicular to the late follicular phase of the cycle (3.4±0.3 v. 4.4±0.2 pulses 6 h P<0.01). During the luteal phase the basal concentration of LH (5.6±0.9 U/l), pulse amplitude (7.4±1.7 U/l) and frequency (1.6±0.2/6 h) were much lower than at any stage of the follicular phase (P<0.001). The concentration of FSH and PRL showed a similar but less marked change to that of LH throughout the menstrual cycle with a significant decline in both basal concentration and pulse frequency in the luteal phase of the cycle. Although only 47% of all LH pulses were associated with a pulse of FSH, 70% of FSH and prolactin pulses occurred within 15 min of an LH pulse.

Mifepristone (RU 486) compared with high-dose estrogen and progestogen for emergency postcoital contraception

Abstract Background. Mifepristone (RU 486) is a synthetic steroid with potent antiprogestational and antiglucocorticoid properties that provides an effective medical method of inducing abortion in early pregnancy. Since progesterone is essential for implantation, we tested the use of mifepristone for emergency postcoital contraception. Methods. We studied 800 women and adolescents requesting emergency postcoital contraception who had had unprotected intercourse within the preceding 72 hours. A total of 398 women and adolescents were randomly assigned to treatment with 100 μg of ethinyl estradiol and 1 mg of norgestrel, each given twice 12 hours apart (standard therapy), and 402 women and adolescents were randomly assigned to receive 600 mg of mifepristone. Results. None of the women and adolescents who received mifepristone became pregnant, as compared with four of those who received standard therapy; the difference in failure rates between the two regimens was not statistically significant. The number of...

PROSTAGLANDIN SYNTHESIS IN THE ENDOMETRIUM OF WOMEN WITH OVULAR DYSFUNCTIONAL UTERINE BLEEDING

The endogenous concentrations of prostaglandins F2α (PGF2α) and E (PGE) were measured during the luteal phase of the menstrual cycle in the endometrium from 14 women with unexplained menorrhagia (measured menstrual blood loss in excess of 50 ml) and 15 women with normal menses (blood loss 50 ml or less). Although there was no significant difference in the PGF 2α/PGE ratio between the two groups, this ratio was significantly lower in the endometrium from eight of the women whose blood loss exceeded 90 ml (p <0.05). There was a significant inverse correlation between the PGF2α/PGE ratio and blood loss (r = 0.36, p <0.025). The synthetic capacity of the endometrium was assessed by incubation of the tissue with 14C arachidonic acid. Endometria from nine women with unexplained menorrhagia synthesized more PGE2 than PGF2α, whereas the converse was true with 11 control endometria. Consequently the PGF2α/PGE2 ratio was significantly reduced in the former group (p <0.025). Oestradiol‐17β (200 μM) and to a greater extent 2 hydroxy oestradiol (200 μM) increased the total prostaglandin synthesis by the endometria, but did not significantly alter the PGF2α/PGE2 ratio. These results suggest that excessive blood loss may be associated with a shift in the endometrial conversion of prostaglandin endoperoxide from PGF2α to PGE2.

Effect of recombinant inhibin on androgen synthesis in cultured human thecal cells

The effect of activin-A on ovarian androgen synthesis was tested in vitro using serum-free monolayer cultures of human thecal cells. Maximal rates of androgen (androstenedione and dehydroepiandrosterone) production were induced by treating the cells for 4 days with LH (10 ng/mL) in the presence of insulin-like growth factor-I (greater than or equal to 30 ng/mL). The additional presence of recombinant activin-A (1-100 ng/mL) in culture medium caused dose-dependent suppression of thecal cell androgen production, with 50% maximal inhibition occurring at an activin-A concentration of about 10 ng/mL. Progesterone production was only suppressed by high dose (100 ng/mL) activin-A, and inhibition of steroid production occurred without inhibition of DNA synthesis (tritiated thymidine uptake). These results reveal a potent and selective inhibitory action of activin-A on thecal cell androgen synthesis, consistent with a paracrine function for activin(s) in modulating follicular androgen biosynthesis in the human ovary.

Regulation of folliculogenesis and the determination of ovulation rate in ruminants.

The paper presents an update of our 1993 model of ovarian follicular development in ruminants, based on knowledge gained from the past 15 years of research. The model addresses the sequence of events from follicular formation in fetal life, through the successive waves of follicular growth and atresia, culminating with the emergence of ovulatory follicles during reproductive cycles. The original concept of five developmental classes of follicles, defined primarily by their responses to gonadotrophins, is retained: primordial, committed, gonadotrophin-responsive, gonadotrophin-dependent and ovulatory follicles. The updated model has more extensive integration of the morphological, molecular and cellular events during folliculogenesis with systemic events in the whole animal. It also incorporates knowledge on factors that influence oocyte quality and the critical roles of the oocyte in regulating follicular development and ovulation rate. The original hypothetical mechanisms determining ovulation rate are retained but with some refinements; the enhanced viability of gonadotrophin-dependent follicles and increases in the number of gonadotrophin-responsive follicles by increases in the throughput of follicles to this stage of growth. Finally, we reexamine how these two mechanisms, which are thought not to be mutually exclusive, appear to account for most of the known genetic and environmental effects on ovulation rate.

Shrinkage of uterine fibroids during therapy with goserelin (Zoladex * ): a luteinizing hormone-releasing hormone agonist administered as a monthly subcutaneous depot

Thirteen premenopausal women with uterine fibroids were treated for a maximum of 6 months with a long-acting agonist of luteinizing hormone-releasing hormone (LH-RH), goserelin (Zoladex depot, ICI Pharmaceuticals, Macclesfield, UK) 3.6 mg, administered subcutaneously every 28 days. A 55% reduction (range, 38% to 84%) in uterine volume assessed by ultrasound was obtained. The greatest reduction (30%) was apparent within the first treatment cycle regardless of whether treatment was started in the early follicular or the luteal phase. Fibroid regression was inversely correlated with urinary estrogen concentration. Treatment was well tolerated and only one subject withdrew from the study before its scheduled completion. Following cessation of therapy, ovulatory menstruation returned within 3 months in the majority of the subjects, but this was accompanied by a rapid regrowth of the fibroids. This medical approach to the management of fibroids merits further investigation but as yet cannot be regarded as an alternative to surgery.

The endocrinology of menstruation – a role for the immune system

The human endometrium displays characteristic features, both structural and functional, across the menstrual cycle. It is the sex steroid hormones, oestrogen and progesterone, that drive the endometrium through the different phases of the cycle. Oestrogen and progesterone act sequentially to regulate cellular concentrations of their respective receptors, this interaction initiates gene transcription. Thereafter a cascade of local events prepares the endometrium for implantation, but in the absence of pregnancy, progesterone withdrawal leads to menstruation and cyclic repair. Withdrawal of progesterone from an oestrogen-progesterone primed endometrium is the initiating event for the cascade of molecular and cellular interactions that result in menstruation. Progesterone withdrawal first affects cells with progesterone receptors. Early events in the menstrual process are vasoconstriction and cytokine up-regulation. The activation of lytic mechanisms is a later event and involves cells that may lack progesterone receptors, for example, uterine leucocytes and epithelial cells. Hence progesterone withdrawal results in a local increase of inflammatory mediators and the enzymes responsible for tissue breakdown. The total complex of local factors implicated in normal menstrual and aberrant menstrual bleeding are yet to be fully defined.

The effects of peri-ovulatory administration of levonorgestrel on the menstrual cycle.

Levonorgestrel (LNG) 0.75 mg administered 12 h apart within 72 h of unprotected coitus, is an established method of emergency contraception (EC). The mechanism of action of LNG used in this manner is unknown. We administered LNG 0.75 mg twice immediately before ovulation, to test the hypothesis that LNG acts as an emergency contraceptive by abolishing the pre-ovulatory lutenizing hormone (LH) surge and thereby delaying ovulation. Twelve women took LNG on or before the day of the first significant rise in urinary LH in 12 cycles. In four women, the LH peak and the onset of next menses were significantly delayed (delay of 16.8 days (SD +/- 8.7) from the day of mean LH peak in placebo cycles). One woman did not ovulate at all, despite a normal LH peak and cycle length. In the remaining eight women, LNG did not affect ovulation or the cycle length, but the length of the luteal phase and the total luteal phase LH concentrations were significantly reduced. We suggest that LNG acts as an emergency contraceptive by other mechanisms as well as delaying the LH surge and interfering with ovulation.

MORPHOLOGICAL AND FUNCTIONAL RELATIONS OF GRAAFIAN FOLLICLE GROWTH TO OVULATION IN WOMEN USING ULTRASONIC, LAPAROSCOPIC AND BIOCHEMICAL MEASUREMENTS

The daily growth rates of ovarian follicles were recorded ultrasonically for five days until ovulation in 56 spontaneously ovulating women and related to endocrine and clinical parameters. Over the 5‐day period, the average diameter of the follicle destined to ovulate increased from 12 to 23 mm, the second largest follicle from 6 to 12 mm, the third largest follicle from 5 to 9 mm and the fourth largest follicle from 4 to 8 mm. Similar but lesser growth rates occurred in the follicles in the contralateral ovary. Ovulation occurred within 24 hours of the luteinizing hormone (LH) peak, and the mean peak diameter of the ovulating follicle was 23.2±0.3 (SEM) mm, (range 18–29 mm) before ovulation, and subsequent luteal function was judged to be normal. Follicular growth was most closely correlated with increasing peripheral blood oestrogen levels. In 16 women who had a laparoscopy within 12 hours of the last ultrasound and following the LH peak, the mean diameter of the largest follicle as measured by ultrasound (23.6±0.4 mm) was similar to that measured at laparoscopy (22.8±0.4 mm) and estimated from the volume of follicular fluid aspirated (average 5.8±0.2 ml), 22.5 mm. The follicular fluid levels of progesterone were high on the day of the LH peak and blood progesterone levels had risen significantly indicating that luteinization of the dominant Graafian follicles had already occurred prior to ovulation. This study confirms that ultrasonic monitoring provides a reliable measure of follicular growth and allows studies correlating morphological changes with both normal and abnormal endocrine function of the human ovary.