Role of gonadotrophins and progesterone in the regulation of morphological remodelling and atresia in the monkey peri-ovulatory follicle

Peri-ovulatory progesterone plays an indispensable role in ovulation and luteinization, possibly by controlling tissue remodelling of the ovulatory follicle. This study was designed to evaluate gonadotrophin- versus progestin-mediated changes to the morphology of the follicle wall during luteinization. Ovaries were obtained from macaques undergoing ovarian stimulation either before (0 h) or up to 36 h following administration of an ovulatory human chorionic gonadotrophin (HCG) bolus with or without a 3beta-hydroxysteroid dehydrogenase inhibitor and a non-metabolisable progestin. Morphological changes occurred within 12 h of HCG in the theca, and around 24 h in the granulosa layer and basement membrane. Steroid depletion resulted in follicles that did not luteinize during the 36 h interval, or alternatively, those that exhibited premature luteinization by 12 h post-HCG. Progestin replacement restored normal morphology, although the presence of antral blood suggested acceleration of normal tissue remodelling. A proportion of pre-ovulatory follicles became atretic after the HCG bolus, although progestin treatment reduced the percentage of atretic follicles. Ovarian stimulation resulted in the development of multiple pre-ovulatory follicles which are heterogeneous in their response to the HCG bolus and local progestin action. Nevertheless, this model supports both anti-atretic and pro-differentiative actions of progesterone in promoting follicular health and remodelling during the development of the corpus luteum.     

Dynamics of periovulatory steroidogenesis in the rhesus monkey follicle after ovarian stimulation

The temporal relationships and regulation of events in the primate follicle during the periovulatory interval are poorly understood. This study was designed to elucidate the dynamics of steroid synthesis in the macaque follicle during ovarian stimulation cycles in which serum/follicular fluid aspirates were collected at precise intervals before (0 h) and after (up to 36 h) administration of the ovulatory human chorionic gonadotrophin (HCG) bolus. Serum concentrations of progesterone increased (P < 0.05) within 30 min, and follicular fluid progesterone concentrations were elevated 180-fold within 12 h, of HCG injection, and remained elevated until the time of ovulation. In contrast, 17beta-oestradiol concentrations increased initially, but then declined (P < 0.05) by 36 h post-HCG. Acute incubation of granulosa cells with and without steroidogenic substrates demonstrated that: (i) 3beta-hydroxysteroid dehydrogenase and aromatase activities were present in equivalent amounts before and after HCG; whereas (ii) P450 side-chain cleavage activity increased (P < 0.05) within 12 h of HCG; and (iii) exogenous low-density lipoprotein and cholesterol were not utilized for steroidogenesis. This model should be useful for further studies on ovulation and luteinization in primates, and enable elucidation of the local actions of progesterone and other steroids at specific time points during the periovulatory interval.     

Preovulatory effects of the progesterone antagonist mifepristone (RU486) in mice.

The progesterone antagonist mifepristone (RU486), was given in mice once on different days of pregnant mare's serum gonadotrophin-human chorionic gonadotrophin (PMSG-HCG) treatment and its action upon the induction of ovulation studied. RU486 administered on the day after PMSG significantly reduced the ovulation rate. Ovulation was completely inhibited when the progesterone antagonist was given simultaneously with HCG, but RU486 administered 4 h after HCG treatment remained ineffective. The development of two-cell zygotes harvested on day 2 post-coitum from mice treated with RU486 on the day after the PMSG treatment was followed in vitro and showed a significant decrease in the number of embryos developing to blastocysts. These results favour the involvement of progesterone in the ovulation process, indicating a direct effect of this hormone at the ovarian level via a progesterone receptor-mediated action.     

Effect of follicular aspiration on hormonal parameters in patients undergoing ovarian stimulation

The effect of follicular aspiration and oocyte retrieval on hormonal parameters was examined in women undergoing ovarian stimulation for in-vitro fertilization (IVF) compared to induced ovulation in women undergoing ovarian stimulation for intrauterine insemination (IUI). Blood samples were collected immediately before and 1 h after oocyte retrieval and 48 h later on the day of embryo transfer in 25 IVF patients and before the insemination and 48 h later in 20 IUI patients. A highly significant fall in serum levels of oestradiol (E2), progesterone (P) and human chorionic gonadotrophin (HCG), (P less than 0.001) was observed in the IVF group 1 h after follicular aspiration. The decline in serum E2 levels was maintained at 48 h. In contrast, there was no significant change in serum E2 levels in the IUI group during 48 h. The immediate decline in E2 levels after follicular aspiration might play a role in preventing ovarian hyperstimulation syndrome.     

In-vitro synthesis of steroid hormones in corpora lutea from normal women and women treated with 300 micrograms norethisterone.

The in-vitro oestradiol (E2) and progesterone (P) production by corpora lutea (CL) obtained at sterilization from 30 untreated women and 43 women treated with norethisterone (NET) 300 micrograms daily was measured. The CL were obtained at different stages of the luteal phase in the untreated women [luteinizing hormone (LH) 0 to +3, n = 7; LH +4 to +7, n = 7; LH +8 to +11, n = 9; LH +12 to menses, n = 7] and on days LH +8 to +11 or cycle days 22 to 26 in the NET-treated women. In the treated women, four types of ovarian reaction were identified. Four women showed ovarian reaction Type A (completely inhibited ovarian activity), 14 women Type B (marked follicular activity, but no luteal function), 12 women Type C (normal follicular activity, followed by insufficient luteal function) and 13 women Type D (apparently normal follicular and luteal activity). The CL were incubated in Eagle's medium with and without stimulation by human chorionic gonadotrophin (HCG) for 2 and 4 h. In the untreated women, P and E2 production increased significantly with both incubation time and stimulation by HCG throughout the luteal phase, except in the late luteal phase (LH +12 to menses) where P increased (P less than 0.01) only after 4 h stimulation by HCG. The maximal production of P was found after 4 h incubation with HCG stimulation of CL tissue in the early-mid luteal phase (LH +4 to +7).(ABSTRACT TRUNCATED AT 250 WORDS)     

Human chorionic gonadotrophin luteal support overcomes luteal phase inadequacy after gonadotrophin-releasing hormone agonist-induced ovulation in gonadotrophin-stimulated cycles

Gonadotrophin-releasing hormone agonist (GnRHa)-induced ovulation after gonadotrophin ovarian stimulation is used to prevent ovarian hyperstimulation syndrome and multiple pregnancy in polyfollicular cycles. However, one of the major problems to be resolved is corpus luteum function after follicular maturation and ovulation by mid-cycle GnRHa administration. The present report investigated the luteal phase in non-conceptual polyfollicular cycles in 26 patients (group 1) receiving a single dose of 0.5 mg leuprolide acetate to induce ovulation and in a control group of patients (n = 26) (group 2) who were given human chorionic gonadotrophin (HCG) (10,000 IU i.m.) for ovulation induction. All of them were normal ovulatory women undergoing gonadotrophin ovarian stimulation because of unexplained infertility or male factor. In both groups of patients two doses of 2500 IU HCG i.m. were given 6 and 10 days after the ovulatory dose of HCG or GnRHa to support the luteal phase. All cycles were ovulatory as shown by mid- luteal serum progesterone concentrations >10 ng/ml. Mean serum progesterone concentrations were 62% higher in group 2 than in group 1, but this difference was not statistically significant. The mean length of the luteal phase was similar in groups 1 and 2. It is concluded that HCG luteal support is a useful tool to overcome the luteal phase inadequacy that characterizes GnRHa-triggered cycles after gonadotrophin stimulation.      

Induction of ovulation in rabbits with pure urinary luteinizing hormone and human chorionic gonadotrophin: comparison of oocyte and embryo quality.

Thirty-six 18-week-old nulliparous does were stimulated with a single dose of 25 IU pregnant mare serum gonadotrophin (PMSG). Ovulation was induced 48 h later with 50 IU luteinizing hormone (LH) (18 does) or 50 IU human chorionic gonadotrophin (HCG) (18 does) in order to determine the effects of pure urinary LH and HCG on the quality of oocytes and embryos. Nine does were mated in each group. The does were slaughtered 24 h after induction of ovulation to recover oocytes and 48 h after mating to recover embryos. The number of haemorrhagic, preovulatory and luteinizing follicles per ovary were recorded. The quality of oocytes and embryos recovered were evaluated. No significant differences in the number of haemorrhagic follicles (blood follicles without stigma), preovulatory and luteinizing follicles were observed between LH and HCG groups. LH has a selective action, which could permit the acquisition of better quality oocytes. Although the fertilization rate was similar in both groups (LH versus HCG), the percentage of degenerate embryos (grade 5) was lower for the LH (3%) than the HCG (13%) groups.     

Is continuation of a gonadotrophin-releasing hormone agonist (GnRHa) necessary for women at risk of developing the ovarian hyperstimulation syndrome?

A total of 28 women scheduled for in-vitro fertilization used buserelin and human menopausal gonadotrophin (HMG) for ovarian stimulation. One group (I) of 17 women was given human chorionic gonadotrophin (HCG 10,000 IU) to trigger ovulation, but the resulting embryos were electively cryopreserved because of the risk (serum oestradiol greater than or equal to 3500 pg/ml) of developing the ovarian hyperstimulation syndrome (OHSS). Six women continued the buserelin therapy in the luteal phase and eleven did not. In group II (n = 11), the HMG injections were discontinued because of an exaggerated ovarian response and the HCG was omitted. Six of these women continued the buserelin injections until the onset of menses and five did not. In both groups, the ovarian response to induction of ovulation (serum oestradiol concentrations and number of follicles) was similar for those who did or did not continue buserelin therapy. There was no difference in the rate of ovarian quiescence (weekly fall in serum oestradiol concentration following the stimulation) between those women who did or did not continue the buserelin therapy in either group. The serum luteinizing hormone concentrations remained low in all women in both groups. We conclude that the omission of buserelin therapy after discontinuing the HMG in women at risk of developing OHSS does not affect subsequent ovarian quiescence.     

Colony stimulating factor-1 concentrations in blood and follicular fluid during the human menstrual cycle and ovarian stimulation: possible role in the ovulatory process.

To evaluate a possible role for colony stimulating factor-1 (CSF-1) in human ovarian function, the peripheral blood CSF-1 concentration throughout the human menstrual cycle and during ovarian stimulation was monitored. Blood was sampled across the menstrual cycle (n = 10) and at specific times during ovarian stimulation. In addition, the CSF-1 concentrations in follicular fluid (FF) during the follicular phase and during the luteinizing hormone (LH) surge of natural cycles, as well as 35-37 h after human chorionic gonadotrophin (HCG) during ovarian stimulation, were determined. There was no significant variation in CSF-1 concentrations during the natural menstrual cycle (median 470, range 212-1364 pg/ml). CSF-1 concentrations in FF (n = 11) were about four-fold higher (P < 0. 0001) than those in plasma of the same patients. CSF-1 concentrations in these FF showed some stage dependent variability, with significantly higher values during the ovulatory phase (median of 2017 pg/ml, range 1131-2236 pg/ml), compared to mid-follicular phase (median 961 pg/ml, range 830-1340 pg/ml; P = 0.02). During ovarian stimulation (n = 20), the plasma concentrations were similar to a time prior to stimulation up to and including 35-37 h after HCG. On day 9 after HCG, the values (median 644, range 357-1352 pg/ml) were significantly higher compared to pre-stimulation (median 422, range 253-1598 pg/ml; P < 0.05) and 35-37 h after HCG (median 458, range 250-658 pg/ml; P < 0.01). FF concentrations (n = 27) of CSF-1 at oocyte retrieval (median 3116, range 1824-5883 pg/ml) were about seven-fold higher than blood concentrations (median 472, range 250-1055 pg/ml; P < 0.0001). These results suggest that the intra-ovarian CSF-1, possibly induced by LH/HCG, plays an important role during ovulation and luteinization.     

Prolactin delays gonadotrophin-induced ovulation and down-regulates expression of plasminogen-activator system in ovary

This study was conducted to determine whether prolactin (PRL) suppresses gonadotrophin-induced ovulation and disturbs the co- ordinated gene expression of tissue type plasminogen activator (tPA) and plasminogen activator inhibitor type-1 (PAI-1) in rat ovary. Immature female rats were injected with 10 IU pregnant mare's serum gonadotrophin to stimulate follicle growth, and 48 h received different doses of prolactin followed by 7 IU human chorionic gonadotrophin (HCG). The oviducts were examined for the presence of ova, and the amounts of tPA and PAI-1 mRNA present in the ovary were measured at various times after the hormone treatment. PRL had no significant effect on ovarian weight but caused a dose-dependent decrease in ovulation number. In the control animals receiving HCG alone, 13.3 +/- 1.3 (mean +/- SEM) ova/oviduct were found; while in animals receiving HCG plus 50, 100 or 200 microg PRL, the ovulation number was dose- dependently suppressed by 53.6, 66.9 and 76% respectively at 18 h after treatment. PRL suppression of HCG-induced ovulation was time-dependent. By 24 h after treatment, the number of ova in the oviducts in HCG- and HCG plus PRL-treated groups was not significantly different. PRL also suppressed HCG-induced tPA gene expression in a dose- and time- dependent manner. At all time points examined, tPA mRNA content of whole ovaries and granulosa cells (GC) in PRL-treated groups was lower than in the HCG-treated controls. The activities of PAI-1 in ovarian extracellular fluid (OEF) and PAI-1 mRNA in the theca-interstitial cells (TI) in the PRL-treated groups were higher than in the HCG- treated controls. The highest stimulation by PRL of PAI-1 activity in OEF and of PAI-1 mRNA in TI was observed at 9 h and 6 h after HCG treatment respectively. The localization of tPA and PAI-1 antigens in the ovaries was consistent with changes in the mRNA and activity levels. These data suggest that PRL temporarily delays, but does not completely inhibit, HCG-induced ovulation, which may be caused by a suppression of PA-mediated proteolysis.      

Endocrinology: Stimulation of ovarian adenylyl cyclase activity by gonadotrophins during the natural and gonadotrophin-induced cycles in the hamster

In this study we utilized the hamster ovary as a model to investigatethe effects of ovulation induction with gonadotrophin on theactivation of the signal transducer effector system, adenylylcyclase (AC). For this purpose, we prepared membrane particlesfrom the ovary and analysed both gonadotrophin-sensitive ACand non-receptor-mediated activation during a cycle in whichovulation and luteinization were achieved by pregnant mare’sserum gonadotrophin (PMSG)/human chorionic gonadotrophin (HCG)administration. Results were directly compared with AC activationin similarly prepared membranes obtained at different stagesof the natural unstimulated cycle. AC activity was quantifiedby the direct conversion of ATP substrate into cyclic adenosinemonophosphate (cAMP). Measurements of ovarian weights, serumoestradiol and progesterone concentrations provided a solidbase from which to evaluate the functional status of the ovaryat each time period during the natural and stimulated cycles.We found that ovarian membranes contain functional componentsof the AC system and demonstrated that AC is highly dependenton hormonal changes and the functional state of the ovary. Thus,during the natural cycle, ovarian AC showed relatively constantresponsiveness to follicle-stimulating hormone (FSH) throughoutthe cycle, whereas responsiveness to luteinizing hormone (LH)/HCGreached its peak during the luteal phase. On the other hand,during the stimulated cycle, sensitivity to FSH and LH/HCG variedconsiderably, being absent during the peri-ovulatory period.AC responsiveness to gonadotrophins was only regained 48 h afterovulation. Also during the peri-ovulatory period of the gonadotrophin-inducedcycle, stimulation of ovarian AC with non-hormonal activatorsdeclined. However, the rate of cAMP production in response tothese activators remained very high, indicating that despiterefractoriness to gonadotrophins, ovarian AC retained the capacityto generate cAMP at near maximal efficiency. Basal (non-stimulated)activity, guanine nucleotide activation, hormone responsivenessand stimulation by the non-hormonal activators NaF and forskolinwere all significantly increased in comparison with the naturalcycle. Basal activity alone was 7-fold higher than the activityobserved during the unstimulated cycle. These results suggestthat subsequent to exogenous gonadotrophin administration, thetransmembrane effector AC system must be primed for a higherlevel of activity in the ovarian tissue. This priming of theovarian AC system by exogenous gonadotrophin was also evidentwhen the enzyme was measured under conditions allowing maximalactivity, i.e. in the presence of a combination of NaF and forskolin.Maximal AC activity increased 4- to 5-fold compared with thenatural cycle. We conclude that gonadotrophin administrationinducing ovulation causes profound alterations in the expressionof AC in ovarian membranes. Gonadotrophin treatment increasedthe enzyme activity and induced a temporal desensitization toFSH and LH/HCG in the peri-ovulatory period of the stimulatedcycle. Because the gonadotrophin-sensitive AC system representsthe capacity of FSH and LH/HCG receptors to couple and elicita biological response, our results provide new insights intothe cellular mechanisms that regulate ovarian activity duringinduction of ovulation.     

A controlled study of human chorionic gonadotrophin induced ovulation versus urinary luteinizing hormone surge for timing of intrauterine insemination.

Forty-eight patients in a programme of intrauterine insemination (IUI) were randomized in a cross-over study. All were stimulated with clomiphene citrate (CC) and inseminated either after follicular rupture induced by human chorionic gonadotrophin (HCG) or after a spontaneous urinary luteinizing hormone (LH) surge. The HCG was administered when follicles of 18-22 mm in diameter were observed on ultrasound and IUI was performed 37-40 h thereafter. The monitoring of a urinary LH peak was carried out using a rapid urinary LH test. IUI took place approximately 22 h after detection of the LH surge. Overall, the pregnancy rates were 9.3% (4/43) after HCG induced ovulation and 20.5% (9/44) after spontaneous ovulation (P = 0.12). Analysis of mid-cycle events showed that following sonographic criteria, the HCG injection was performed significantly earlier in the cycle compared with the spontaneous LH surge. In addition, the mean diameter of the preovulatory follicles was significantly smaller and insemination was substantially earlier in the HCG induced cycles. These findings suggest that a beneficial effect arises from allowing the natural process of final follicular maturation to occur.     

The synergistic effects of clomiphene citrate and human menopausal gonadotrophin in the folliculogenesis of stimulated cycles as assessed by the gonadotrophin-releasing hormone antagonist Nal-Glu.

Clomiphene citrate (CC), alone or in combination with exogenous gonadotrophins, has been widely used in ovulation induction. CC promotes endogenous release of gonadotrophins, yet when used in combination with exogenous gonadotrophins, its contribution to folliculogenesis is difficult to assess. In order to determine the contribution of CC-induced endogenous gonadotrophin production to the overall ovarian stimulation in cycles treated with CC/human menopausal gonadotrophin (HMG), Nal-Glu, a gonadotrophin-releasing hormone (GnRH) antagonist was administered. Fertile women (n = 10) undergoing ovarian stimulation and oocyte aspiration for the sole purpose of gamete donation were studied. Five women received CC (100 mg daily for 5 days) in conjunction with pure follicle stimulating hormone (FSH) 150 IU daily. Five women received HMG alone. Nal-Glu (50 micrograms/kg/day) was administered intramuscularly to both groups when the leading follicles reached a mean diameter of 16 mm. Human chorionic gonadotrophin (HCG) 10,000 IU was given when the largest follicles reached a mean diameter of 20-22 mm. A significant fall in serum oestradiol levels was observed in women given CC/FSH (37.9 +/- 7.3%) within the first 24 h of Nal-Glu administration. Serum luteinizing hormone (LH) decreased greater than 20% within 24 h of Nal-Glu administration and remained low throughout the rest of the treatment. No decrease in oestradiol levels was noted in cycles receiving HMG alone. With supplemental FSH, falling oestradiol levels in CC/FSH cycles rebounded and continued to rise until the day after HCG administration. Despite a drop in oestradiol in CC/FSH cycles, the aspirated oocytes exhibited no untoward effects. The fertilization and cleavage rates were similar, and pregnancies occurred in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Does ovarian stimulation for in-vitro fertilization induce a hypercoagulable state?

Effects on blood coagulation and fibrinolytic activity during ovarian stimulation for in-vitro fertilization (IVF) were examined in 12 women. Blood samples were taken prior to hormonal stimulation (days 2-3 of the menstrual cycle, mean serum oestradiol concentration 0.16 nmol/l) and the day after ovulation induction with human chorionic gonadotrophin (HCG) (days 10-12, mean serum oestradiol concentration 5.35 nmol/l). We measured whole blood clotting time, whole blood clot lysis time, plasma fibrinogen, factor VII and antithrombin III. The whole blood clotting time was slightly, but not significantly shortened after ovarian stimulation. A significant rise in plasma fibrinogen (P less than 0.001) and reduction in antithrombin III (P less than 0.001) were observed, whereas no change in factor VII was found. The blood fibrinolytic activity was significantly reduced as evaluated by an increase in the clot lysis time (P less than 0.02). These results indicate that ovarian stimulation for IVF may create a state of hypercoagulability.     

Endocrinology: The influence of human chorionic gonadotrophin administration upon the next ovarian cycle

We examined the influence of human chorionic gonadotrophin (HCG),used as an ovulation inducer and/or for supporting the lutealphase, on the next ovarian cycle. Four women received 10 000IU of HCG at mid-cycle and another four received the same doseplus 1500 IU on the 17th, 19th and 21th days of the cycle. Inthe menstrual cycle prior to our experiments, venous blood sampleswere collected and vaginal ultrasound of the ovaries was performedevery other day from day 21–28; the same data were alsocollected on days 1–10 of the experiment cycle. In sucha way, control values were obtained. After the administrationof HCG, venous blood samples were collected and ultrasound wasperformed in the same way and on the same days as in the controls.Follicle stimulating hormone (FSH) and luteinizing hormone weredetermined by radioimmunoassay in all blood samples, and HCGonly in samples collected after the experiment. The resultsshowed that only FSH was lower in the late luteal phase afterthe administration of 10 000 IU of HCG. Follicular diameterswere higher during the follicular phase than during the previouscycle only in women who received the low dose of HCG. In addition,one woman presented with detectable HCG in the following ovariancycle. The use of HCG in the preceding cycle may reduce FSHand develop persistent follicles in the subsequent cycle. Wesuggest that an ultrasound of the ovaries should be performedbefore starting a new ovulation induction cycle in a woman whohas received HCG in the previous cycle. Our results also implythat the ‘biochemical pregnancy’ could be a falsepregnancy.     

Uterine contractility decreases at the time of blastocyst transfers

High-frequency uterine contractions at the time of non-cavitating embryo transfer influence adversely IVF-embryo transfer outcome. This prompted us to quantify prospectively the possible decline in uterine contraction frequency occurring during later stages of the luteal phase of ovarian stimulation, up to the time of blastocyst transfers, in 43 IVF-embryo transfer candidates. Contractility was assessed on the day of human chorionic gonadotrophin (HCG) administration, 4 days after HCG (non-cavitating embryo transfer; HCG + 4), and 7 days after HCG (blastocyst transfers; HCG + 7). For this, 2 min sagittal uterine scans were obtained by ultrasound and digitized with a computerized system for the assessment of uterine contraction frequency. Our results indicated that a slight, yet significant, decrease in uterine contraction frequency, observed from the day of HCG (4.4 +/- 0.2 contractions/min) to HCG + 4 (3.5 + 0.2 contractions/min), was followed by a more pronounced, additional decrease between HCG + 4 and HCG + 7 (1.5 +/- 0.2 contractions/min; P < 0.001). In conclusion, during the luteal phase of ovarian stimulation, uterine contractility decreases progressively, and reaches a nearly quiescent status 7 days after HCG administration, at the time of blastocyst transfers. It is possible that such a uterine relaxation assists blastocyst implantation.     

A pilot study of the human chorionic gonadotrophin test for ovarian hyperandrogenism

A controlled clinical study was designed to investigate the value of human chorionic gonadotrophin (HCG) challenge as a test for functional ovarian hyperandrogenism. Dexamethasone administration was followed by 5000 IU HCG and blood samples for steroid hormone assay were obtained 0, 8, 16, and 24 h thereafter. Study subjects were normal women (n = 13); women with functional ovarian hyperandrogenism, defined by androgen excess, amenorrhoea and an increased 17-hydroxyprogesterone response to nafarelin (n = 6); and normal men (n = 4). The responses of 17-hydroxyprogesterone, androstenedione and testosterone to HCG in women with functional ovarian hyperandrogenism were significantly greater than in normal women. However, the 17-hydroxyprogesterone response to HCG in functional ovarian hyperandrogenism was significantly lower after HCG than after nafarelin. The oestradiol response was also significantly lower after HCG than nafarelin, although oestradiol concentration more than doubled in normal women as well as in women with functional ovarian hyperandrogenism. The responses to HCG confirm that functional ovarian hyperandrogenism abnormalities are luteinizing hormone (LH)-dependent. Therefore, the 17- hydroxyprogesterone response to HCG could represent a useful test for the diagnosis of ovarian hyperandrogenism. The lower 17- hydroxyprogesterone response to HCG than to nafarelin in functional ovarian hyperandrogenism suggests that a follicle-stimulating hormone (FSH)-responsive factor modulates thecal 17-hydroxyprogesterone secretion. The oestradiol response to HCG is consistent with HCG directly stimulating the oestradiol secretion by thecal cells.      

The effect of progesterone supplementation prior to the induction of ovulation in women treated for in-vitro fertilization

Thirty-one patients superovulated with clomiphene citrate (CC)and human menopausal gonadotrophin (HMG) were given a singleinjection of 25 mg progesterone (P group) 6 h prior to injectionof human chorionic gonadotrophin (HCG). Levels of urinary andplasma luteinizing hormone (LH) were significantly higher (P<0.001)immediately prior to HCG in the P group compared with thirty-onecontrol patients who had HCG on the same night. Plasma levelsof progesterone remained significantly elevated (P<0.02)for 80 h after injection in the P group, thereafter the levelwas similar to controls. The number of oocytes recovered, fertilizedand replaced per patient was identical in both groups. However,four control patients had no embryos replaced due to failedfertilization. It is concluded that (i) in the majority of Ppatients the timing of ovulation induction by HCG injectionwas appropriate as an LH surge was elicited thus reflectinga physiological stage of readiness, and (ii) elevated plasmaprogesterone levels around the time of oocyte recovery and inthe early luteal phase do not increase the likelihood of theestablishment of pregnancy in patients stimulated for in-vitrofertilization and embryo replacement (TVF/ER) with CC and HMG.     

Human chorionic gonadortrophin measurements in the luteal phase of the menstrual cycle of infertile and fertile women

Serum human chorionic gonadotrophin (HCG) determinations wereperformed every other day during the luteal phase of the menstrualcycle of 20 women suffering from unexplained infertility andof 20 women assumed to be fertile. HCG was determined by a specificradioimmunoassay which applied an antiserum directed againstthe HCG subunit. The group of infertile patients demonstrateddetectable serum HCG in only three cases. No clinically confirmedpregnancies were achieved in this group. Eighteen of the 20women presumed to be fertile showed detectable HCG levels. Fiveof these achieved ongoing pregnancies, while 13 women revealedincreased HCG levels without delayed menstrual periods. Thefirst day of detection of HCG during the luteal phase did notdiffer between the two groups. In the five women with ongoingpregnancies the time of detection of HCG ranged from day 5 untilday 12 after ovulation. It is concluded that the high rate ofincreased HCG values in the fertile group may represent earlyconceptual loss, but the apparently disorderly HCG results indicatethe need for cautious interpretation of HCG determinations duringthe luteal phase. Furthermore, early conceptual loss forms nomajor explanation for unexplained infertility.     

An intravital microscopy method permitting continuous long-term observations of ovulation in vivo in the rabbit

BACKGROUND: A method for intravital microscopy of the rabbit ovary was developed to enable observations of real-time changes during ovulation in vivo. The aim was to correlate these events to biochemical events at specific stages of ovulation. METHODS: Virgin, female rabbits were primed with equine chorionic gonadotrophin (CG) (30-100 IU) then HCG (100 IU) 2 days later to induce ovulation. During anaesthesia, the right ovary was surgically exteriorized and submerged in an organ chamber with a microscopy lens positioned close to the ovary. Continuous video recordings were performed. RESULTS: Initial equine CG priming experiments revealed the highest ovulation rate, without premature luteinization, after 30 IU equine CG. This priming protocol subsequently demonstrated follicular ruptures 11.5-14 h after HCG. Numbers of ovulations from the exteriorized and contralateral non-exteriorized ovary were similar. The sequence of typical features of ovulation was: shutdown of microcirculation in the follicular apex, formation of petechiae in the follicular wall and a cone-shaped structure over the future rupture site, marked bleeding in connection with follicular rupture and a fairly steady extrusion velocity of granulosa cells and the oocyte. CONCLUSION: This method captured a sequence of structural changes during ovulation. It could be combined with blood and follicular fluid sampling for biochemical analysis and could be used in studies on biochemical reactions in relation to specific changes in the follicular structure during ovulation.