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PubMed1990

Interference with ovulation by sequential treatment with the antiprogesterone RU486 and synthetic progestin.

Seven healthy women were treated with the antiprogesterone RU486, 25 mg/d, on days 1 to 14 of the follicular phase of the menstrual cycle, followed by the synthetic progestin NET in the luteal phase of the cycle. Venous blood samples were collected twice per week. Serum E2, P, and RU486 concentrations were determined by RIAs, and FSH and LH by immunofluorometric assays. Ultrasonography was used to measure the sizes of the follicles. Serum concentrations of FSH and LH were not suppressed during the treatment. Ovulation was apparently suppressed during RU486 treatment according to E2 and P concentrations and ultrasonography findings. During NET treatment, some evidence of ovulation and follicle growth were found during the first treatment periods. During the third treatment cycle, there was no evidence of ovulation (n = 2). Estradiol concentrations were sufficient to stimulate normal proliferative growth of the endometrium during the treatment. Control of bleeding was good. The exact mechanism of action of RU486 on steroid synthesis and ovulation is not clear, but it appears to act at the ovarian level. The evidence indicates that sequential RU486/progestin treatment could be developed to result in suppression of follicular growth and ovulation.

Adult↗
PubMedDate not supplied

The reliability of menses to indicate the return of ovulation in breastfeeding women in Manila, The Philippines.

Demographic studies generally use menses to indicate the return of fertility during breastfeeding. In a prospective study of 40 breastfeeding women in Manila, the resumption of ovarian activity was monitored by urinary hormone assays, and menstrual status was determined by weekly interview. For the women who menstruated before six months postpartum, first menses was not a good indicator of ovulation because there was a high proportion of anovular menses (67 percent), and the lag between anovular first menses and subsequent ovulation was 15.7 (+/- 4.4) weeks. After six months postpartum the proportion of anovular first menses declined to 22 percent, and the lag between anovular first menses and ovulation was 7.3 (+/- 4.6) weeks. If all anovular and ovulatory menstrual episodes are considered, the mean interval between first observed menses and first ovulation was 8.4 weeks during the first six months postpartum and only 0.1 week after six months. Thus, in breastfeeding women, menses is an inaccurate proxy measure for the timing of fertility return before six months postpartum, but a good indicator of the resumption of ovulation after six months.

Amenorrhea↗
PubMed1986

[Parameters of ovulation in clomiphene citrate treated cycles. The effect of pre-ovulatory administration of oestrogen and human chorionic gonadotropin].

This study was undertaken to evaluate the parameters used for monitoring ovulation in patients on clomiphene citrate treatment for the induction of ovulation. The mean serum oestradiol level for every follicle larger than 17 mm on the day before ovulation was 1 885 pmol/l. This value is significantly higher than the value found in spontaneous cycles. The maximum average pre-ovulatory follicle size was 22 mm, also significantly larger than in spontaneous cycles. The maximum pre-ovulatory cervical mucus score is significantly lower than that found in spontaneous cycles. The average midluteal serum progesterone and oestradiol values were significantly higher than in spontaneous cycles. These differences should be taken into consideration in interpreting the results of patients treated with clomiphene citrate for ovulation abnormalities and before in vitro fertilization. Seven patients with a healthy cervix had poor cervical mucus scores in spite of high pre-ovulatory serum oestradiol levels; scores did not improve with administration of exogenous oestrogen, but became optimal with subsequent human menopausal gonadotrophin treatment. Poor cervical mucus despite ovulation and adequate pre-ovulatory serum oestradiol levels in patients on clomiphene treatment should therefore be considered as an indication for gonadotrophin treatment. Pre-ovulatory administration of human chorionic gonadotrophin had no effect in increasing midluteal serum progesterone and oestradiol levels.

Cervix Mucus↗
PubMed1985

[Mechanisms regulating ovulation rate and oocyte maturation. Maturation induction and superovulation].

The follicular growth takes longer in most mammals than it does in rodents: (4 to 15 days between the antral stage and ovulation in rodents, versus 65 days in women). The ovulation rates typical of animal species are mainly regulated during two critical periods: antrum formation and a few days before ovulation. The FSH level appears to be determinant, but in the animal species or races whose ovulation rate is near one, a dominant follicle is involved in the atresia of others. Increasing the level of gonadotrophins, especially of FSH, results in superovulation. However, the results are often irregular, with prolonged maturations and ovulations and oocytes of uncertain quality. Using pituitary gonadotrophins instead of placental or urinary hormones considerably increases the number of oocytes available and improves the development of embryos if the FSH/LH ratio of pituitary gonadotrophins is adjusted to the species involved. Thus, the main problem concerns the quality of the oocyte. At the present time, no criterion allows a prediction of the quality of the oocyte, and the complexity of the mechanisms involved in its intrafollicular maturation do not foreshadow a simple and rapid solution. However, appreciable improvements in our techniques are possible on the basis of current knowledge.

Animals↗
PubMed1981

Neuroendocrine control of human ovulation.

Ovulation, defined as the release of a mature oocyte from a ruptured Graafian follicle at the surface of the ovary, is the culmination of the process of follicular maturation. The latter is under the synergistic influence of the pituitary gonadotropins, follicle stimulating hormone (FSH), and luteinizing hormone (LH), the secretion of which is, in turn, stimulated by the hypothalamic decapeptide, LH-releasing hormone (LH-RH). There is a complex interrelationship between the ovarian steroid hormones, estradiol and progesterone, and the gonadotropins, with estradiol exerting both negative and positive feedback effects on the hypothalamo-pituitary unit. Ovulation is triggered by a surge of LH which results from at least two estradiol-induced phenomena, increased hypothalamic production of LH-RH and increased pituitary responsiveness to releasing hormone. Ovulation occurs 16-17 hours following the LH peak and the probability of conception following an act of coitus appears to be maximal 1-2 days prior to ovulation itself. States of anovulation are frequently seen in association with hyperprolactinemia whereas ovulation may be delayed under a variety of circumstances.

Adult↗
PubMed1980

Temporal relationships between ovulation and defined changes in the concentration of plasma estradiol-17 beta, luteinizing hormone, follicle-stimulating hormone, and progesterone. I. Probit analysis. World Health Organization, Task Force on Methods for the Determination of the Fertile Period, Special Programme of Research, Development and Research Training in Human Reproduction.

One hundred seventy-seven women have been studied over the periovulatory period, in order to obtain detailed information on temporal relationships between ovulation and defined changes in the concentrations of estradiol-17 beta (E2), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and progesterone (P) in peripheral plasma. Serial samples of blood were taken, the surfaces of the ovaries were examined at laparotomy, and the mature follicle or corpus luteum was removed for histologic examination. The results in 107 cases fulfilled the criteria for statistical analysis, and in 78 the operation was performed after the follicle had ruptured. A probit analysis was undertaken with use of the proportion of women who had ovulated at a given time in relation to the interval from a defined rise or peak in the concentration of a circulating hormone. The median time intervals (in hours) from the hormonal event to ovulation and the 95% confidence limits of the estimates are as follows: 17 beta-estradiol--rise 82.5 (54.0 to 100.5), peak 24.0 (16.9 to 32.1); LH--rise 32.0 (23.6 to 38.2), peak 16.5 (9.5 to 23.0); FSH--rise 21.1 (14.1 to 30.9), peak 15.3 (8.1 to 21.7); progesterone--rise 7.8 (-12.5 to 15.9). From the statistical model for LH it was possible to estimate that ovulation in 90% of the cases had occurred between 16 (+/- 6) and 48 (+/- 6) hours after the first significant rise in the concentration of this hormone and between -3 (+/- 5) and 36 (+/- 5) hours after the peak. An examination of the individual results in every woman gave corresponding ranges of between 24 and 56 hours from the first significant rise in LH and between 8 and 40 hours after the peak. From a practical standpoint, the conclusion is that a defined rise in the concentration of circulating LH is the best indirect parameter of impending ovulation.

Adult↗
PubMed1980

[Dual action of prostaglandins in the regulation of HCG-induced ovulation in immature rats (author's transl)].

With the aid of indomethacin, a potent inhibitor of prostaglandin synthesis, the mechanism of action of prostaglandins on follicle rupture was studied. Mean number of ova shed following treatment of immature rats sequentially with PMS and hCG was reduced in a dose-dependent manner by simultaneous injection with increasing doses of indomethacin. The minimum effective dose to block ovulation completely was 90 micrograms. However, the anti-ovulatory action of the minimum effective dose at 0 h became progressively less potent as the time between hCG injection and indomethacin administration was increased. Another dose-dependent relationship was found 10 h after hCG injection, the closest time prior to the onset of ovulation, the minimum effective dose necessary to prevent ovulation was 8 times higher than at 0 h, suggesting that prostaglandins acted differently on ovulation in the later stage of the preovulatory process. It is concluded that prostaglandins may mediate the action of hCG on ovulation at least through two mechanisms.

Animals↗
PubMed1981

Fertilizability of ova from young or old hamsters after spontaneous or induced ovulation.

Young or aged hamsters, subjected to spontaneous or induced ovulation, were examined for ovulation rate, fertilization rate, and chromosomal normality. The fertilization rate in aged animals was decreased but there were no differences in ovulation rate. Abnormal chromosomes and degenerated oocytes occurred in the aged animals after induced ovulation. The fertilizing ability of sperm incubated in the uteri of young or aging animals showed no obvious differences when used for in vitro fertilization. These results indicated that defective ova represent one of the major factors leading to increased preimplantation loss in aged animals and also that superovulation of aged animals results in no beneficial effect, over spontaneous ovulation, on the fertilization process.

Age Factors↗
PubMed1997

Incidence of spontaneous ovulation in young, group-housed cats based on serum and faecal concentrations of progesterone.

Cats are considered to be reflex ovulators that exhibit a luteal phase (pregnancy or pseudopregnancy) only after copulatory stimulation. In a group-housed colony of 15 1-year-old domestic queens, 23 noncopulatory, spontaneous ovulations were observed in 87% of the queens over 4.5 months based upon the detection of increased concentrations of progesterone in faeces, serum, or both. Luteal phases were detectable for periods of 3 to 5 weeks with peak progesterone concentrations averaging 21 +/- 1 ng ml-1 in serum and 1874 +/- 281 ng g-1 in faeces. Individual cats exhibited from 0 to 3 spontaneous ovulations and subsequent pseudopregnancies each. A male was added to a separate cage within the room during the last 1.5 months of the study. The incidence of ovulation per 10 day period ranged from 0% to 22% before introduction of the male and from 33% to 57% immediately after introduction of the male, suggesting a potential noncopulatory influence of the male on the incidence of spontaneous ovulation in young, group-housed cats.

Animals↗
PubMed2006

Improved monofollicular ovulation in anovulatory or oligo-ovulatory women after a low-dose step-up protocol with weekly increments of 25 international units of follicle-stimulating hormone.

OBJECTIVE: To compare the effectiveness and efficiency of two low-dose step-up protocols for ovulation induction in women with anovulatory infertility (World Health Organization group II). DESIGN: Open-label, prospective, randomized, group-comparative, multicenter study. SETTING: Eighteen infertility centers in Europe and Canada. PATIENT(S): One hundred fifty-eight anovulatory or oligo-ovulatory infertile women. INTERVENTION(S): Patients were randomly assigned to one of two protocols for one cycle of follitropin beta (rFSH) using a pen device. The starting dosage was 50 IU/day for 7 days. In the absence of follicles > or =12 mm, the daily dosage was increased by either 25 or 50 IU per week. MAIN OUTCOME MEASURE(S): The percentage of all subjects treated who ovulated after one treatment cycle (efficacy) and the total rFSH dose to reach ovulation (efficiency). RESULT(S): The 25-IU group had a higher incidence of monofollicular growth (41.3% of 80 vs. 21.8% of 78 women) and ovulation (81.3% vs. 60.3%), a lower cumulative rFSH dose (887 IU vs. 984 IU), and fewer cancellations due to hyperresponse (>3 follicles > or =15 mm; 5.0% vs. 20.5%). Both protocols were well tolerated. CONCLUSION(S): Weekly increments of 25 IU in the daily dose were more effective and efficient than 50-IU increments.

Adolescent↗
PubMed2000

Gonadotrophin therapy for ovulation induction in subfertility associated with polycystic ovary syndrome.

BACKGROUND: Approximately 15% of patients with PCOS remain anovulatory despite treatment with oral anti-oestrogen medications such as clomiphene citrate. In addition, about half of women with PCOS ovulating on anti-oestrogen treatment fail to conceive. Gonadotrophin stimulation is the next step in treatment for women who are "clomiphene resistant", however, results of gonadotrophin stimulation in women with PCOS are less successful. In PCOS associated with hypersecretion of LH, purified urinary follicle-stimulating hormone (u-FSH) preparations have theoretical advantages over the use of human menopausal gonadotrophin (hMG) preparations (containing both FSH and LH), but whether this claimed advantage extends into clinical practice remains uncertain. In addition, the use of gonadotrophin-releasing hormone analogues (GnRH-a) to produce pituitary desensitisation prior to ovulation induction in PCOS has been claimed to increase the success rates of treatment as well as reduce complications such as OHSS and multiple pregnancy. Gonadotrophin preparations have also been administered via different routes (intramuscular or subcutaneous), or using different stimulation regimens and protocols (step-up or standard) in an attempt to improve efficacy. OBJECTIVES: To determine the effectiveness of urinary-derived gonadotrophins as ovulation induction agents in patients with PCOS trying to conceive. In particular, to assess the effectiveness of (1) different gonadotrophin preparations, (2) the addition of a gonadotrophin-releasing hormone agonist (GnRH-a) to gonadotrophin stimulation and (3) different modalities of gonadotrophin administration. SEARCH STRATEGY: The search strategy to identify RCTs consisted of (1) the Group's Specialised Register of Controlled Trials using the search strategy developed for the Menstrual Disorders and Subfertility Group as a whole (see the Review Group details for more information), (2) additional specific electronic Medline searches and (3) bibliographies of identified studies and narrative reviews. SELECTION CRITERIA: RCTs in which urinary-derived gonadotrophins were used for ovulation induction in patients with primary or secondary subfertility attributable to PCOS. DATA COLLECTION AND ANALYSIS: Twenty three RCTs were identified, 9 of which were excluded from analysis. The data were extracted independently by 2 authors. The following criteria were assessed: (1) the methodological characteristics of the trials, (2) the baseline characteristics of the studied groups and (3) the outcomes of interest: pregnancy rate (per cycle), ovulation rate (per cycle), miscarriage rate (per pregnancy), multiple pregnancy rate (per pregnancy), overstimulation rate (per cycle) and ovarian hyperstimulation syndrome (OHSS) rate (per cycle). Where suitable, meta-analysis was performed using Peto's OR with 95% CI with the fixed effect Mantel-Haentszel equation. MAIN RESULTS: (1) A reduction in the incidence of OHSS with FSH compared to hMG in stimulation cycles without the concomitant use of a GnRH-a (OR 0.20; 95% CI 0.08-0.46) and (2) a higher overstimulation rate when a GnRH-a is added to gonadotrophins (OR 3.15; 95% CI 1.48-6.70). REVIEWER'S CONCLUSIONS: Although 14 RCTs were included in this review, few dealt with the same comparisons, all were small to moderate size and their methodological quality was generally poor. Any conclusions, therefore, remain tentative as they are based on a limited amount of data and will require further RCTs to substantiate them. In none of the comparisons was there a significant improvement in pregnancy rate but this may be due to the lack of power (i.e. insufficient patients randomised to demonstrate a significant difference between treatments). There was a trend towards better pregnancy rates with the addition of a GnRH-a to gonadotrophin stimulation and these interventions warrant further study. Despite theoretical advantages, urinary-derived FSH preparations did not improve pregnancy rates when compared to traditional and cheaper hMG preparations; their only demonstrable benefit was a reduced risk of OHSS in cycles when administered without the concomitant use of a GnRH-a. No conclusions can be drawn on miscarriage and multiple pregnancy rates due to insufficient reporting of these outcomes in the trials.

Female↗
PubMed2000

Pulsatile luteinising hormone releasing hormone for ovulation induction in subfertility associated with polycystic ovary syndrome.

BACKGROUND: In normal menstrual cycles, gonadotrophin releasing hormone (GnRH) secretion is pulsatile, with intervals of 60-120 minutes in the follicular phase. Treatment with pulsatile GnRH infusion by the intra-venous or subcutaneous route using a portable pump has been used successfully in patients with hypogonadotrophic hypogonadism. Assuming that the results would be similar in polycystic ovary syndrome (PCOS), pulsatile GnRH has been used to induce ovulation in patients with PCOS. But, although ovulation and pregnancy has been achieved, the use of pulsatile GnRH in PCOS patients is controversial. OBJECTIVES: To assess the effectiveness of pulsatile GnRH administration in women with clomiphene-resistant polycystic ovary syndrome (PCOS), in terms of ovulation induction, pregnancy, miscarriage, multiple pregnancy and ovarian hyperstimulation syndrome (OHSS). SEARCH STRATEGY: The search strategy of the Menstrual Disorders and Subfertility review group was used to identify all relevant trials. Please see Review Group details. SELECTION CRITERIA: All relevant published RCTs were selected. Non-randomised controlled trials were eligible for inclusion if treatment consisted of GnRH administration versus another treatment to induce ovulation in subfertile women with PCOS. DATA COLLECTION AND ANALYSIS: A computerised MEDLINE and EMBASE search was used to identify randomised and non randomised controlled trials. The reference lists of all studies found were checked for relevant articles. One RCT (Bringer 1985a) and one abstract (Coelingh 1983) were identified this way. Relevant data were extracted independently by two reviewers (NB, MW). Validity was assessed in terms of method of randomization, completeness of follow-up, presence or absence of cross-over and co-intervention. All trials were screened and analysed for predetermined quality criteria. DATA SYNTHESIS: 2X2 tables were generated for all the relevant outcomes. Odds ratios were generated using the Peto modified Mantel-Haenszel technique. MAIN RESULTS: Three RCTs and one non-randomised comparative trial were identified comparing four different treatments: GnRH versus HMG, GnRH following GnRHa pre-treatment versus no pre-treatment, GnRH and FSH versus FSH, and GnRH following GnRHa pre-treatment versus GnRH following oral contraceptive pre-treatment. This means that there was only one trial in any one comparison. In the first two studies, data of pre- and post-cross-over were not described separately. Therefore, these results could not be included in the MetaView analysis. The odds ratio for ovulation rate was 16 (95 % CI: 1.1-239) in the study comparing GnRH and FSH with FSH. When GnRH after GnRHa pre-treatment was compared with GnRH after oral contraceptive pre-treatment, an odds ratio of 7.5 (95 % CI: 1.2-46) was obtained. All trials were small and of too short duration to show any significance in pregnancy results. Per study only one to four pregnancies occurred. Multiple pregnancies were not seen. OHSS was seen only in the patients stimulated with HMG. REVIEWER'S CONCLUSIONS: The four trials describing four different comparisons with a short follow up (1 to 3 cycles) were too small to either prove or discard the value of pulsatile GnRH treatment in patients with polycystic ovary syndrome.

Female↗
PubMed2004

Pulsatile gonadotrophin releasing hormone for ovulation induction in subfertility associated with polycystic ovary syndrome.

BACKGROUND: In normal menstrual cycles, gonadotrophin releasing hormone (GnRH) secretion is pulsatile, with intervals of 60-120 minutes in the follicular phase. Treatment with pulsatile GnRH infusion by the intravenous or subcutaneous route using a portable pump has been used successfully in patients with hypogonadotrophic hypogonadism. Assuming that the results would be similar in women with polycystic ovary syndrome (PCOS), pulsatile GnRH has been used to induce ovulation in these women. Although ovulation and pregnancy have been achieved, the effectiveness of pulsatile GnRH in women with PCOS has not been clearly demonstrated. OBJECTIVES: To assess the effectiveness of pulsatile GnRH administration in women with polycystic ovary syndrome (PCOS), in terms of ongoing pregnancy, ovulation, clinical pregnancy, ovarian hyperstimulation syndrome (OHSS), multiple pregnancy, miscarriage, and multifollicular growth. SEARCH STRATEGY: We searched the Cochrane Menstrual Disorders & Subfertility Group trials register (searched 13 August 2003), the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 2, August 2001), MEDLINE (January 1966 to August 2003), EMBASE (January 1985 to August 2003) and reference lists of articles. We also contacted manufacturers and researchers in the field. SELECTION CRITERIA: All relevant published randomised clinical trials were selected for inclusion if treatment consisted of pulsatile GnRH administration versus another treatment for ovulation induction in subfertile women with PCOS. DATA COLLECTION AND ANALYSIS: Relevant data were extracted independently by two reviewers (NB, MW). Validity was assessed in terms of method of randomisation, completeness of follow-up, presence or absence of crossover and co-intervention. All trials were screened and analysed for predetermined quality criteria. DATA SYNTHESIS: 2X2 tables were generated for all the relevant outcomes. Odds ratios were generated using the Peto method. MAIN RESULTS: Four randomised clinical trials involving 57 women were identified comparing four different treatments: GnRH versus HMG, GnRH and FSH versus FSH, GnRH following pretreatment with GnRH agonist (GnRHa) versus GnRH only, GnRH following pretreatment with GnRHa versus clomiphene citrate. This means that there was only one trial in any one comparison. In two studies, data of pre- and post-crossover were not described separately. All trials were small and of too short duration to show any significant differences in pregnancy results. The odds ratio for ongoing pregnancy, only described in one trial, was 7.5 (95% CI 0.44 to 127) in the comparison GnRH following pretreatment with GnRHa versus GnRH only in favour of the first group. Multiple pregnancies were not seen. Ovarian hyperstimulation syndrome was seen only in women allocated to ovulation induction with HMG. REVIEWER'S CONCLUSIONS: The four trials describing four different comparisons with a short follow up (1 to 3 cycles) were too small to either prove or discard the value of pulsatile GnRH treatment in patients with polycystic ovary syndrome.

Female↗
PubMed1984

Steroidogenesis in granulosa cells during follicular maturation: evidence for desensitization-resensitization during the ovulation cycle.

Output of progesterone, the end product of the steroidogenic pathway, was studied in isolated chicken granulosa cells in relation to follicular maturation and during the ovulation cycle with particular reference to the period between the LH peak and ovulation. The evidence gathered from a series of experiments conducted during the past 2-3 years in the authors' laboratory indicate that the steroidogenic capacity of granulosa cells during follicular maturation is regulated not so much by receptor-coupled adenylate cyclase activity as has been proposed by other investigators, but by the activity of key steroidogenic enzymes, particularly the cholesterol 20,22 desmolase. Furthermore, granulosa cells undergo cyclic sensitization following the endogenous LH surge reaching maximal responsiveness about 1 hr before oviposition. This is followed by a rapid desensitization shortly before ovulation. This desensitization extends to the second and subsequent developing follicles probably in proportion to the evolving LH receptors. It is suggested that granulosa cells remain in such a desensitized state for several hours postovulation, during which time progesterone responses to LH are attenuated and consequently ovulation does not occur prematurely. It is proposed that this intraovarian mechanism is an important component of the physiological events that regulate the ovulation cycle in the domestic fowl.

Adenylyl Cyclases↗
PubMed1990

Effect of maternal age on the incidence of digynic triploidy in LT/Sv strain mice: implications for the ovulation of primary and secondary oocytes in this strain.

LT/Sv strain mice ovulate both primary and secondary oocytes, which are fertilisable, giving rise to digynic triploid and normal diploid fertilised conceptuses, respectively. Since the proportion of primary and secondary oocytes ovulated in our earlier studies varied widely among females, we investigated whether the proportion of primary oocytes ovulated in LT/Sv strain mice was influenced by maternal age. Females 6, 12, 18, 24, and 30 weeks old were mated with F1 hybrid males. The females were autopsied on the 10th day of gestation, and the intact conceptuses or extraembryonic membranes analysed cytogenetically. Since no selective loss of the triploids occurs up to the 10th day of gestation, analysis at this time also provides indirect information on the proportion of primary and secondary oocytes ovulated. We observed 1) that the overall incidence of triploidy decreased from 55% in the 6-week-old females to 6% in the 30-week-old group; 2) that the number of females from which both triploid and diploid embryos were recovered decreased with increased maternal age; 3) that a substantial decrease in the proportion of triploid embryos was observed in those females in which both triploid and diploid embryos were recovered, in relation to increased maternal age; 4) that there was no overall decrease in the total number of implants with increasing age; and 5) that there was no increase in the incidence of resorptions with increasing maternal age. We believe that no comparable relationship between the ovulation of primary and secondary oocytes and maternal age has previously been reported.

Animals↗
PubMed2001

Distribution of lectin-binding glycosidic residues in the hamster follicular oocytes and their modifications in the zona pellucida after ovulation.

In the present study, we have employed a battery of colloidal gold-tagged lectins as probes in conjunction with quantitative analysis to demonstrate the distribution and changes of carbohydrate residues in the hamster zona pellucida (ZP) during ovarian follicular development and during transit of the oocyte through the oviduct after ovulation. High-resolution lectin-gold cytochemistry performed on thin sections of LR White-embedded ovaries revealed a moderate to strong reactivity to WGA, PNA, DSA, AAA, and MAA over the entire thickness of the ZP of ovarian oocytes at different stages of follicular development. Labeling intensity over the ZP progressively increased as follicles matured in the ovary. In parallel, there was an association of labeling by gold particles with cortical granules, stacks of Golgi saccules, and complex structures called vesicular aggregates in the oocyte proper especially during the late stages of follicular growth. In contrary, labeling with each of HPA, DBA, and BSAIB(4) was absent in the ovary but was found to be localized over Golgi complexes and secretory granules in the non-ciliated secretory cells of the oviduct. When ovulated oocytes were labeled with each of HPA, WGA, RCA-I, PNA, DSA, BSAIB(4), AAA, MAA, and DBA, the ZP and several organelles in the oocyte proper presented a differential distribution of lectin-binding sites. Quantitative analysis was also performed on labeling by lectin-gold complexes that bind specifically to the ZP of mature follicular and ovulated oocytes. Quantitative evaluation revealed heterogeneous labeling between the inner and the outer zone of the ZP. A significant increase in the labeling densities in both inner and outer ZP was noted when tissue sections of ovulated oocytes were labeled with RCA-I or AAA. Tissue sections of ovaries labeled with WGA demonstrated a significant increase in the density of labeling in the outer layer of the ZP. Labeling by PNA, DSA, and MAA, however, showed a significant decrease in both the inner and outer portions of the ZP. Together, these results suggest that in the hamster, glycoproteins carrying specific sugar residues are added to the ZP of ovarian follicles during the early stages of folliculogenesis and are processed through a common secretory machinery, and that there is a significant change in both the sugar moieties and distribution of glycoproteins in the ZP following ovulation. Our results also showed that the hamster oviduct plays an important role in contributing certain glycoproteins to the ZP suggesting that the sugar moieties of these oviductal glycoproteins may have functional significance in fertilization.

Animals↗
PubMed2006

Remodeling of extracellular matrix at ovulation of the bovine ovarian follicle.

Using immunohistochemistry and RNA analyses we examined the fate of components of a newly identified matrix that develops between granulosa cells (focimatrix, abbreviated from focal intraepithelial matrix) and of the follicular basal lamina in ovulating bovine ovarian follicles. Pre- and postovulatory follicles were generated by treatment with estradiol (Day 1), progesterone (Days 1-10), and prostaglandin analogue (Day 9) with either no further treatment (Group 1, n = 6) and or with 25 mg porcine LH (Day 11, Group 2, n = 8 or Day 10, Group 3, n = 8) and ovariectomy on Day 12 (12-14 hr post LH in Group 2, 38-40.5 hr in Group 3). In the time frame examined no loss of follicular basal lamina laminin chains beta2 and gamma1 or nidogen 1 was observed. In the follicular basal lamina collagen type IV alpha1 and perlecan were present prior to ovulation; after ovulation collagen type IV alpha1 was discontinuously distributed and perlecan was absent. Versican in the theca interna adjacent to the follicular basal lamina in preovulatory follicles was not observed post ovulation, however, the granulosa cells then showed strong cytoplasmic staining for versican. Expression of versican isoforms V0, V1, and V3 was detected at all stages. Focimatrix was observed in preovulatory follicles. It contained collagen type IV alpha1, laminins beta2 and gamma1, nidogen 1 and perlecan and underwent changes in composition similar to that of the follicular basal lamina. In conclusion focimatrix and the follicular basal lamina are degraded at ovulation. Individual components are lost at different times.

Animals↗
PubMed1999

Toxic equivalency factors of polychlorinated dibenzo-p-dioxins in an ovulation model: validation of the toxic equivalency concept for one aspect of endocrine disruption.

Polychlorinated dibenzo-p-dioxins (PCDDs) are structural analogues, which produce a similar spectrum of biological and toxicological responses in animals, albeit with differential potencies. Very consistent structure-activity relationships have been found for acute toxicity and some biochemical effects among these compounds. For the current experiments, the gonadotropin-primed immature female rat model was used to study the effect of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), 1,2,3,7, 8-pentachlorodibenzo-p-dioxin (PeCDD), and 1,2,3,4,7, 8-hexachlorodibenzo-p-dioxin (HxCDD) on ovulation. Single doses of different PCDDs and their mixture were given orally to 23-day-old rats. Gonadotropin from pregnant mare's serum (PMSG) was injected (5 IU) 24 h later to induce follicular maturation. Rats were decapitated at various times after PMSG, blood was collected, and ovarian weight was measured. Serum concentrations of 17beta-estradiol (E2), progesterone (P4), luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PrL) were determined by radioimmunoassay. Ovulation was measured at 72 h after injection of PMSG by counting ova flushed from oviducts. PCDDs dose dependently decreased the number of ova per ovary and reduced ovarian weight gain induced by PMSG. The slopes of the dose-response curves generated by individual PCDDs and/or their mixture were similar. PMSG-induced increase in serum E2 was enhanced on the day of expected ovulation by PCDDs; in contrast, serum P4 and FSH were decreased at that same time point. PCDDs also altered the temporal pattern of serum E2, FSH, and LH but not that of PrL. Histologically the effect of all three PCDDs consisted of ova trapped in preovulatory follicles and a lack of or reduced number of corpora lutea. The results indicate that the PCDDs, tested in the present model, have the same mode of action on ovulation and the reproductive hormones, e.g., LH, FSH, P4 and E2. Furthermore, the dose responses of the individual congeners are parallel to each other and also to that of their equipotent mixture, which represent a validation of the TEQ concept for one aspect of endocrine disruption, that is for inhibition of ovulation.

Animals↗