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PubMed1999

[Follicular dynamics after treatment with hCG for ovulation induction in mares].

In this study the use of hCG for induction of ovulation is described. Factors such as follicle diameter at the time of administration of hCG (3000 IE hCG i.v.), follicular growth after hCG and the rate of double ovulations were evaluated. A total of 168 mares presented for artificial insemination were used. In 249 estrous periods hCG was given to mares exhibiting standing estrous when a minimum follicle diameter of 30 mm and a well developed edema of the endometrium could be detected by ultrasonography. In nine estrous periods ovulation occurred within 24 hours after hCG. The majority of mares (216; 86.7%) ovulated 24 to 48 hours after hCG and in 24 cases ovulation was delayed beyond 48 hours. Follicle size at the time of hCG administration (30-34 mm, 35-39 mm, > or = 40 mm) had no influence on the percentage of mares ovulating 24 to 48 hours after hCG (89.2%, 87.9%, and 83.7%, respectively). Double ovulations could be observed in 17.7% of estrous periods. The one cycle pregnancy rate was not influenced by follicle size (small 45.9%; medium 41.6%; large 47.5%). Repeated treatments with hCG during successive estrous cycles within one year did not influence the rate of responding to hCG. Mares in standing estrous respond well to hCG if a minimum follicle size of 30 mm and a well developed endometrial folding is present.

Animals↗
PubMed2000

[Ovulation induction and the risk of ovarian tumors].

In the last years it has been observed a more and more increasing number of women submitted to therapies for induction of ovulation (disorders of the ovulation represent 33% of the causes of female infertility). In 1998, these therapies had been administrated to approximately two million of USA women. Various Authors have assumed a possible relationship between induction of ovulation and ovarian tumors. Between 1982 and 1997, at least 43 cases of ovarian tumors have been published (among these, there were also 25 cases of epithelial tumors) occurring in women previously treated with ovulation induction. The mean age of patient was 30.3 years, approximately 20 years younger than normal patient population for the same tumors. Among the possible causes of epithelial ovarian tumors, there is the trauma of the ovary surface caused by the continuous repeating of the ovulation phenomenon (incessant ovulation). Gynecologist should be aware of this potential risk for their patients. Multicentric studies should be evaluated in order to establish the risk of ovarian cancer in women treated for infertility problems. A survey of the international literature is made in order to analyse the epidemiological studies and to discuss the relationship between ovulation inducing agents and ovarian tumors.

Adult↗
PubMed1975

The morphology of follicular development and ovulation in non-human primates.

A colony of Macaca fascicularis have been under continuous observation for the past 4 years to ascertain the follicular morphological changes that occur prior to ovulation and during the development of the corpus luteum. Of 609 experimental cycles, laparoscopy was performed at least once in 44-5% of the cycles. Of the 104 cycles where the ovulatory status was definitely known, 89-4% were deemed ovulatory and 10-6% anovulatory. The presence or absence of ovulation in the previous cycle did not have an effect on the cycle length either for the total cycles or when analysing only cycles over 28 days. Similarly, the occurrence of two consecutive ovulations (in consecutive cycles) on the same vs. opposite ovaries did not have a significant effect on the cycle length. Neither laparoscopic stress or anaesthesia effected the normal cyclicity of the animals. The characteristic changes in follicular morphology are most clearly defined in M. fascicularis. In this species the 24 of 36 hr prior to ovulation are accompanied by discrete changes which occur in a fixed sequence, allowing one to predict the time of ovulation with reasonable accuracy. In S. sciureus ovulation is preceded by extensive bulging at the follicular apex and haemorrhaging at the base of the follicle. Due to this haemorrhaging post-ovulatory follicles in S. sciureus are generally more easily discernible than in fascicularis. The formation of clear areas (stigma) is not as evident in either S. sciureus or G. senegalensis as in the macaque. Actual ovulation has been observed four times in M. fascicularis and twice in S. sciureus.

Animals↗
PubMed2004

Luteolysis, onset of estrus, and ovulation in Holstein heifers given prostaglandin F2alpha concurrent with, or 24 hours prior to, removal of an intravaginal, progesterone-releasing device.

The objective was to determine the effects of giving prostaglandin F2alpha (PGF) concurrent with, or 24 h before, removal of an intravaginal, progesterone-releasing (controlled internal drug release [CIDR]) device, on luteolysis, the synchrony of estrus and ovulation. Eighteen postpubertal Holstein heifers were given a CIDR and 100 microg gonadotropin releasing hormone (GnRH) and equally allocated to 3 groups. The PGF was given concurrently with CIDR removal after 7 or 8 d (groups D7/D7 and D8/D8, respectively) or given 1-d before removal of CIDR after 8 d (group D7/D8). There was no difference (P > 0.75) among groups in the intervals (h) from CIDR removal to onset of standing estrus and to ovulation (49.3 h+/-6.2 h and 77.5 h+/-9.0 h, respectively; least squares means+/-standard error of means). We also determined if stage of the estrus cycle influenced the synchrony of estrus or ovulation. In heifers in metestrus at CIDR insertion (versus those at estrus or diestrus), intervals from CIDR removal to estrus and to ovulation were longer by 33.4 h (P < 0.05) and 38.5 h (P = 0.01), respectively. However, the interval from standing estrus to ovulation was not affected. Giving PGF concurrent with CIDR removal did not affect luteal regression, the synchrony of estrus, and ovulation; but heifers in metestrus at the initiation of treatment had longer intervals from CIDR removal to estrus and ovulation.

Animals↗
PubMedDate not supplied

[Follicle dynamics and characteristics of ovulation in heifers after Ovsynch treatment in the last third of the estrous cycle].

The objective of the experiment was to study follicular dynamics and characteristics of ovulations in dairy heifers after application of the Ovsynch protocol in the last third of estrous cycle. Therefore, altogether 27 regular cycling Holstein heifers were given an injection of GnRH on day 14, 16 or 18 (9 heifers each in group 1 to 3) of the estrous cycle. All heifers were administered PGF2alpha seven days later. Blood was collected for progesterone determination, just before, 24 hours and 48 hours after the PGF2alpha injection. A second injection of GnRH was administered 48 hours after the PGF2alpha injection. Ovarian follicular dynamics were monitored by frequent ultrasound scanning of the ovaries after first and second GnRH injection. Altogether 22 of 27 heifers (81.5%) ovulated 27 to 33 h after first GnRH injection. In 4 heifers ovulations were recorded 45 to 51 h after first GnRH application. Mean intervals between GnRH application and ovulation were 33.0, 33.6 and 28.3 h, respectively. At the time of PGF2alpha injection mean progesterone concentrations were similar in groups 1 and 2, but significantly lower than in group 3. After the second GnRH treatment 5,6 and 8 heifers had ovulations. The average intervals from the second GnRH treatment to ovulation were 24.8, 24.0 and 24.4 h respectively. The results show that Ovsynch is not sufficient to ensure synchronisation of oestrous and ovulation in each animal treated.

Animals↗
PubMed1990

[The role of platelet activating factor in ovulation].

Ovulation is associated with inflammation-like changes. Platelet activating factor (PAF) participates in the inflammatory process. We evaluated the potential role of PAF in PMSG-HCG induced ovulation with CV3988, a specific PAF receptor antagonist in hyperovulated ICR mice (9-12 weeks old). Furthermore, we investigated whether prostaglandins (PGs) interfered with the ovulation induced by PAF. CV3988 blocked the ovulation in a dose dependent manner, and the significantly reduced ovulatory efficiency was observed at a dose greater than 500 micrograms (p less than 0.001). The ovulatory efficiency reduced by CV3988 (at a dose of 500 micrograms) was recovered by PAF in a dose dependent manner. PGs production in ovary was increased in reversing the blockade of ovulation with CV3988. These results suggest that PAF may be involved in the ovulation process and PGs may not potentiate the ability of PAF to play a role in ovulation.

Animals↗
PubMed1986

[Effect of PGF2 alpha on ovulation and collagenolytic activities in the rabbit treated by indomethacin].

To clarify a regulatory role of prostaglandins in collagenolytic enzyme activities of the follicular wall at ovulation, we studied whether the ovulation-blocking effect of indomethacin (IM) on hCG-stimulated rabbits could be reversed by an intravenous infusion of PGF2 alpha. The activities of BANA hydrolase and DNP peptidase were also measured by using synthetic substrates N-benzoyl-DL-arginine-2-naphthylamide HCl (BANA) and DNP-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg-OH (DNP peptide), respectively, every hour during the specific preovulatory period. The ovulation-blocking effect of IM (4mg/kg) was reversed by an intravenous infusion of PGF2 alpha (1.5 mg/kg) starting at 3 hr after the hCG injection. In the control rabbits treated with hCG(100 iu) alone, these enzymatic activities were increased toward ovulation with the peak level 7-9 hr after a hCG injection and decreased significantly at 10 hr. The preovulatory increase in these enzymatic activities disappeared following the ovulation-blocking doses of indomethacin. By the addition of the PGF2 alpha infusion, the IM-induced changes in BANA hydrolase and DNP peptidase activities were returned close to the control. It is suggested that the preovulatory increases in BANA hydrolase and DNP peptidase are mandatory for ovulation and PGF2 alpha facilitates ovulation through its regulatory action on these enzymes.

Aminopeptidases↗
PubMed1986

Ultrasound: a technique useful in determining the side of ovulation.

It is often assumed that ovulation commonly occurs from alternating sides each month, but it is unknown whether it can occur repeatedly from the same side. In an effort to answer this question, we selected 39 women from our infertility clinic who had six consecutive courses of ultrasound (US) to monitor ovulation and in whom the side of ovulation was recorded. Nine patients (23.1%) ovulated from the same side for six consecutive cycles, whereas no patient alternated side of ovulation in the same period of time. Stimulation with clomiphene citrate and/or human menopausal gonadotropin that results in single ovulation did not affect this pattern. The data were analyzed statistically with the use of a Markov Chain Model and the chi-square goodness-of-fit; the occurrence of persistent same-side ovulation was significant to P less than or equal to 0.001.

Adult↗
PubMed1979

Precoital single doses of delta9-tetrahydrocannabinol block ovulation in the rabbit.

delta9-Tetrahydrocannabinol (delta9-THC) inhibits pituitary gonadotropin secretion in castrated rhesus monkeys. Also, delta9-THC blocks the ovulatory reflux in rabbits. We report now the dose-response relationship of precoital single doses of delta9-THC on luteinizing hormone (LH) release and ovulation in the rabbit. Forty-five female rabbits in estrous were divided into nine groups of five animals. Groups 1 to 5 received a single intramuscular dose of delta9-THC (5,2.5, 1.25, 0.612, and 0.306 mg/kg, respectively) 2 hours before mating; animals of group 6 received vehicle only. In animals of groups 7 and 8 ovulation was induced with 100 IU of human chorionic gonadotropic (hCG), given intravenously 2 hours after the administration of delta9-THC (5 mg/kg) or vehicle. Rabbit luteinizing hormone (rLH) was measured in plasma 90 to 120 minutes after coitus or hCG administration. After the injection of 5 mg of delta9-THC, luteinizing hormone-releasing factor (LH-RF) (20 microgram intravenously) was administered to the animals of group 9. All animals of groups 6, 7, and 8 ovulated. A dose-response curve was observed in the animals treated with delta9-THC and natural mating. Whereas none of the animals treated with 5 or 2.5 mg/kg ovulated, one of the group treated with 1.25 mg/kg, two of the group treated with 0.612 mg/kg, and all treated with 0.312 mg/kg ovulated. Ovulations correlated with postcoital levels of rLH. All animals of group 9 ovulated, indicating that the site of action of delta9-THC is suprapituitary, probably hypothalamic.

Animals↗
PubMed1982

Survey of antiinflammatory agents and related drugs as inhibitors of ovulation in the rabbit.

A wide variety of antiinflammatory agents and related compounds were administered to rabbits so that their ability to inhibit ovulation could be evaluated. In order of decreasing effectiveness, ovulation was inhibited by the nonsteroidal antiinflammatory agents diclofenac, indomethacin, fenoprofen, niflumate, tolmetin, phenylbutazone, naproxen, meclofenamate, ibuprofen, and flufenamate. Ovulation was not inhibited by aspirin, salicylate, or mefenamate, nor by the steroidal antiinflammatory agents dexamethasone (DEX) and prednisolone. The antineoplastic agents colchicine and vinblastine inhibited ovulation, but not azathioprine, 6-mercaptopurine, or cyclophosphamide. Contrary to previous reports, ovulation was not inhibited by the antihistamines chlorpheniramine, diphenhydramine, or cimetidine. Among the miscellaneous agents tested, ovulation was strongly inhibited by cycloheximide and slightly by acetaminophen but not by clomiphene, quinacrine, allopurinol, diethylstilbestrol (DES), heparin, melatonin, papaverine, chloroquine, D-penicillamine, or levamisole. These results show that ovulation can be inhibited by agents that inhibit acute inflammatory reactions.

Animals↗
PubMed1984

[Annual variations in estrual behavior, rate and possibilities for ovulation in Peulh ewes from Niger].

Annual variations in estrous and ovulation behavior were studied in 23 bicolored Peulh ewes for a period of 30 months. The percentages of estrus and ovulation shown over a year of observation were 76 and 86%, respectively. The average rate of ovulation was 1.3 +/- 0.04 (X +/- SEM). Reproductive activity was minimal from January to April, as the percentages of estrus and ovulation varied between 43.8 and 61% and between 53.1 and 86%, respectively. This period was marked by the advent of anestrus, interrupted frequently by silent and irregular ovulations. Anestrus lasted an average of 81.9 +/- 9.8 days (X +/- SEM). Reproductive activity was maximal from May to December, as the percentages of estrus and ovulation varied between 77 and 97% and between 87.5 and 100%, respectively. During this period ovarian activity was interrupted by prolonged diestrus which lasted an average of 24.9 +/- 3.3 days (X +/- SEM). The ovulation rate did not differ significantly (P greater than 0.05) between periods of minimal and maximal sexual activity. These results suggest that the reproductive potentialities of Peulh sheep on a good diet are comparable to those of certain ovine breeds in temperate zones. The results also suggest that anestrus in bicolored Peulh sheep is probably a different physiological process than the one observed in some breeds of sheep in which anestrus is marked by total ovarian inactivity.

Anestrus↗
PubMedDate not supplied

[Effect of lutropins on oocyte maturation and ovulation in various carp-like fishes in vitro and in vivo].

The study of biological effect of LH and iso-LH isolated from the hypophyses of higher vertebrates on two zoons of carp-like lower vertebrates, has shown that both preparations injected in vivo induce maturation of female loaches, while in the carp, iso-LH stimulates fish maturation and LH single and/or repeated doses (2-3 injections) do not provoke female maturation. Both preparations in vitro stimulate the maturation process and the loach oocyte ovulation, but the character of this effect is dissimilar. LH exerts a high stimulating effect on the loach oocyte maturation and a low one on ovulation. Iso-LH possesses a more complicated biologic effect, depending on its concentration in the medium. Within the limits of 0.01 to 0.2 mg/ml concentrations stimulation of 50% oocyte ovulation is observed (80% ovulating normally), while within 0.5 to 4-5 mg/ml concentrations a more pronounced ability to stimulate the maturation process, but almost the same capability as in the first concentration limits to stimulate the ovulation process, is seen. A comparison of the biological effects of both preparations on the carp oocytes in vitro has shown LH to possess marked maturation-stimulating activity and almost complete absence of ovulation-stimulating action, while iso-LH to be less active as a maturation process stimulant, but to exert a high stimulating effect on ovulation process of mature oocytes.

Animals↗
PubMed1978

In vitro reversal of indomethacin-blocked ovulation by prostaglandin F2alpha.

An in vitro perfused ovary preparation was used to study the role of prostaglandin F2alpha (PGF2alpha) in follicle rupture. The administration of PGF2alpha alone has been shown to restore indomethacin-blocked ovulation in rabbits and monkeys. In the model used, ovulation consistently occurred when human chorionic gonadotropin (hCG) was given to the intact rabbit prior to ovarian removal. hCG-induced ovulation was blocked in both perfused and in situ control ovaries by indomethacin (10 mg/kg intravenously 6 hours after hCG) given to the intact animal. The addition of PGF2alpha (1 mg/200 ml) to the perfusion fluid restored ovulation in the isolated ovary as compared with the in situ ovary (P less than 0.005) and with the perfused, untreated ovary (P less than 0.01). Following removal and perfusion of both ovaries from rabbits treated with indomethacin, ovulation occurred following the addition of PGF2alpha to the perfusate, but did not occur without PGF2alpha (P less than 0.05). These data indicate that indomethacin can block ovulation and that ovulation can be restored by the addition of PGF2alpha to the perfusion system, further supporting the significance of PGF2alpha in the process of follicular rupture.

Animals↗
PubMed1975

Current research in coitus-induced ovulation: a review.

Against the background of renewed interest in the existence of reflex ovulation in many animal species and the possibility of its existence in man, this review on current research efforts embraces the multitude of nervous influences and stimuli accompanying cohabitation. Species showing reflex ovulation are not restricted to those using this as the sole ovulatory mechanism, but include also so-called facultative ovulators, which seem to use this mechanism as a last resort to assure reproductive capacity under adverse situations (rat); and species which for the length of the standing heat period become temporarily induced ovulators for the optimal coordination of all necessary steps to assure fertility (cattle, pig, sheep); and species in which frequent cohabitation (rat) or a single coitus after artificial insemination (sheep) assures either optimal ovulation or conception rates. Copulation might not always be essential; some of the cohabitation-related reflexes might be transmitted by olfactory, ocular, tactile and acoustic stimuli; emotions may play a role. These stimuli are transmitted to the CNS from the periphery by afferent nervous pathways, and are translated in the thalamic-hypothalamic-pituitary complex into neurohormonal phenomena, causing ovulation; or may cause, mainly by LH and/or oxytocin discharge, an acceleration or augmentation of processes involved in spontaneous ovulation. Intensive biochemical and pharmacological studies have unveiled some of the neurohormonal mechanisms involved in the hypothalamus and how these stimuli are transmitted to the pituitary or received at the ovarian level, as hormonal or neurohormonal phenomena.

Amenorrhea↗
PubMed1993

Effect of constant administration of a gonadotropin-releasing hormone agonist on reproductive activity in mares: induction of ovulation during seasonal anestrus.

The potential of a gonadotropin-releasing hormone (GnRH) agonist (goserelin acetate), delivered constantly for 28 days via a subcutaneous depot, to induce ovulation in seasonally anestrous mares, was investigated. Two experiments were conducted, in which a range of doses (30 to 240 micrograms/mare/d) was examined. Mares were selected on the basis of lack of substantial follicular development (follicle diameter < 20 mm determined ultrasonically) and low serum concentrations of luteinizing hormone (LH) and progesterone. Constant administration of the GnRH agonist-induced ovulation in anestrous mares, but a dose-response relation was not observed. Furthermore, with identical doses tested in consecutive or alternate years, considerable variation was observed in the ovulatory response. In general, ovulation in all treated mares was accompanied by increased circulating concentrations of LH and a decrease in follicle-stimulating hormone values. Ovulation was preceded by an increase in estradiol and LH concentrations. In mares in which ovulation did not occur, concentration of LH increased during agonist treatment, whereas that of follicle-stimulating hormone either increased or did not change. It was concluded that constant administration of GnRH agonists may induce ovulation in mares during seasonal anestrus; however, percentage of mares ovulating and the lack of reproducibility of effect indicate that this approach is inappropriate for use as a reliable method to manipulate breeding activity in commercial broodmares.

Anestrus↗
PubMed1996

Timing of induced ovulation in C.B-17/Icr-scid/scid and B6SJLF1 mice.

The time of induced ovulation after superovulation was evaluated in 3- to 8-week-old C.B-17/Icr-scid/scid and B6SJLF1 mice. Mice received intraperitoneal injections of 5 IU of equine chorionic gonadotropin (CG) followed by 5 IU of human (h) CG 48 h apart. Hormones were administered at 1700. Mice were kept on a 14-h light cycle, with lights off at 1900. Nine mice of each strain were sacrificed (3 mice x 3 replicates) at 8, 10, 12, 14, and 16 h after hCG injection. Ovaries and oviducts from each mouse were removed and placed in M-2 collection medium in one well of a 9-well Pyrex culture plate. The oviducts were flushed with M-2 medium, and the number of oocytes from each mouse was counted under a binocular Nikon dissecting microscope. Both mouse strains began ovulating at 8 h after hCG administration. Ovum counts peaked at 12 h in B6SJLF1 mice and at 16 h in C.B-17/Icr-scid/scid mice. A statistically significant strain difference between mean oocytes collected was detected at 10 and 12 h. For both time points, differences were at the 1% level of significance. There was no difference in the mean number of oocytes collected at 14 and 16 h. The mean number of ovulated oocytes increased markedly between 10 to 12 h after hCG in B6SJLF1 mice. The number of ovulated oocytes also increased in C.B-17/Icr-scid/scid mice, although more gradually. These results suggest that the timing of ovulation may be more tightly controlled in superovulated B6SJLF1 than in C.B-17/Icr-scid/scid mice. Superovulated C.B-17/Icr-scid/scid mice finish ovulation 2 to 4 h later than do B6SJLF1 mice. Therefore the best time to harvest pronuclear embryos should be 14 to 16 h after hCG administration in C.B-17/Icr-scid/scid mice and 12 h after hCG in B6SJLF1 mice. To optimize fertilization, mating should occur within 3 h of ovulation and should be planned from 11 to 17 h after hCG for C.B-17/Icr-scid/scid mice and 9 to 15 h after hCG in B6SJLF1 mice. Because male and female pronuclei form 4 to 7 and 6 to 9 h respectively after insemination, the most pronuclear stage embryos should be obtained by collecting them 20 to 21 h after hCG in C.B-17/Icr-scid/scid mice and 18 to 19 h in B6SJLF1 mice.

Animals↗
PubMed1997

Expression of oestrus and timing of ovulation in pigs.

Oestrus is the period around ovulation in which sows show a standing response for boars, thus allowing the boars to mate with the sows. The duration of oestrus may vary between sows from 24 h up to 96 h, which is not related to systemic oestrogen concentrations. The moment of ovulation after onset of oestrus may vary from 10 h to 85 h. Consequently, onset of oestrus is not a good predictor for the time of ovulation. A reliable prediction of ovulation time would be worthwhile, since fertilization results are highly dependent on the moment of insemination relative to the moment of ovulation. However, at present, the duration of oestrus is the best 'predictor' of ovulation time and is independent of the duration of oestrus; ovulation takes place on average 70% of the way through oestrus. The following factors have been found to influence the duration of oestrus (and consequently the optimal time for insemination): boar-stimuli, stress, interval from weaning to oestrus, season and parity. Further study is needed to determine the causes of the variability in oestrus expression between sows, including the regulation of oestrus behaviour at the level of the brain.

Animals↗
PubMed1989

Prediction of ovulation.

The purpose of this investigation was to evaluate all available ovulatory diagnostics with respect to sensitivity, specificity, diagnostic specificity (predictive value of a positive test, PVP) and diagnostic sensitivity (predictive value of a negative test, PVN). Twenty-one ovulatory women with more than 3 years of infertility problems were included in the study. PVP and PVN were highest for detection of urinary luteinizing hormone (LH) peak at ovulation (PVP = 90%, PVN = 95%) and for serum-estradiol peak 1 day before ovulation (PVP = 83%, PVN = 97%). The predictive values were lower for all other tests. The PVP (54%) and PVN (90%) were rather low for detection of ovulation with vaginal electric impedance. However, all ovulations were predicted when urinary LH peak and vaginal impedance were combined. Two women were stimulated with human chorionic gonadotropin to investigate a possible connection between the LH peak and the preovulatory vaginal electric impedance. No close connection between them could be demonstrated. Basal body temperature should not be used for the prediction of ovulation (PVP = 25%). We suggest that ovulation should primarily be predicted from the identification of the urinary LH peak and that other methods be supplementary.

Analysis of Variance↗