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PubMed2005

Ovulation failure and double ovulation in dairy cattle: risk factors and effects.

Ovulation failure and double ovulation rates were examined in 1917 inseminations performed in high-yielding dairy cows under standard commercial conditions. The ovulation rate was determined 11 days post-insemination by ultrasound detection of at least one corpus luteum in the ovaries. Analyzing the double ovulation and pregnancy rates, the study population consisted only of ovulated cows (n = 1792). Data were analyzed using logistic regression methods. A failure to ovulate was recorded in 125/1917 (6.5%) services: 82/663 (12.4%) during the warm and 43/1254 (3.4%) during the cool period. Based on the odds ratios, the risk of ovulation failure was 3.9 times higher for inseminations performed during the warm period. No significant effects of estrous synchronization, milk production and days in milk at AI, and service and lactation number on ovulation failure were found. Double ovulation was recorded in 277/1792 (15.5%) services: 146 (52.7%) unilateral double ovulations (42.5% left versus 57.5% right); 115 (41.5%) bilateral double ovulations; and 16 (5.8%) triple ovulations. Double ovulation was recorded in 72 (12.4%) and 205 (16.9%) AI during the warm and the cool period, respectively. The percentages of double ovulation for first, second and third or more lactations were 6.7, 16.6 and 25%, respectively. Double ovulation rates for early (less than 90 days), mid- (90-150 days) and late (more than 150 days) lactation periods were 13, 20.7 and 14.2%, respectively. Reaching estrus during the warm period decreased the likelihood of double ovulation by a factor of 0.86; the risk of double ovulation was lower in cows with higher milk production (a 1 kg increase in milk yield led to a 0.97-fold reduced risk of double ovulation); cows in their second and in their third or more lactations showed a likelihood of double ovulation (using the first lactation as reference) increased by factors of 3.4 and 5.6, respectively; and reaching estrus during the early and late lactation period was related to a decreased probability of double ovulation (using the mid-lactation period as reference) by factors of 0.56 and 0.84, respectively. No significant effects of synchronization and service number on the double ovulation rate were found. Pregnancy was recorded in 914/1792 (51%) services: rates of 53.5% (811/1515) were recorded for single ovulations; 37.2% (103/277) for double ovulations: 28.8% (42/146) for unilateral double ovulations; 45.2% (52/115) for bilateral double ovulations; and 56.3% (9/16) for triple ovulations. The likelihood of pregnancy diminished in cows: inseminated during the warm period (by a factor of 0.5); inseminated by one particular bull (by a factor of 0.33); with higher milk production (a 1 kg increase in milk yield decreased the probability of pregnancy by a factor of 0.98); or undergoing unilateral (by a factor of 0.31) and bilateral (by a factor of 0.64) double ovulation. Logistic regression analysis indicated no significant effects of synchronization, days in milk, lactation number and service number on pregnancy rate. Collectively, our results indicate that cows showing estrus in conditions of heat stress had a high risk of ovulation failure. The effect of milk production on double ovulation was negative, whereas lactation number was positively correlated with this factor; the highest incidence of double ovulation occurring during the mid-lactation period.

Animals↗
PubMed2000

Laparoscopic "drilling" by diathermy or laser for ovulation induction in anovulatory polycystic ovary syndrome.

BACKGROUND: Problems in inducing ovulation in women with polycystic ovary syndrome (PCOS) and anovulation (failure to ovulate) are well recognised. Surgical ovarian wedge resection was the first established treatment for anovulatory PCOS patients but was largely abandoned of the risk of post-surgical adhesion formation. It was replaced by medical ovulation induction with clomiphene and gonadotrophins. However patients with PCOS treated with gonadotrophins often have a polyfollicular response and are exposed to the risks of ovarian hyperstimulation syndrome (OHSS) and multiple pregnancy. Although effective, it is an expensive, stressful and time consuming form of treatment requiring intensive monitoring. A new surgical therapy, laparoscopic ovarian "drilling", may avoid or reduce the need, or facilitate the use, of gonadotrophins for inducing ovulation. The procedure can be done on an outpatient basis with less trauma and fewer postoperative adhesions. It has been claimed in many uncontrolled observational studies that it is followed, at least temporarily, by a high rate of spontaneous postoperative ovulation and conception, or that subsequent medical ovulation induction becomes easier. OBJECTIVES: To determine the effectiveness of laparoscopic ovarian drilling for ovulation induction in subfertile women with anovulation (failure to ovulate) and polycystic ovarian syndrome (PCOS). SEARCH STRATEGY: The search strategy of the Menstrual Disorders and Subfertility Group was used for the identification of randomised controlled trials (RCTS). A computerised MEDLINE search was used to identify non randomised controlled trials. SELECTION CRITERIA: Trials were eligible for inclusion if treatment consisted of laparoscopic ovarian drilling in order to induce ovulation in subfertile women with PCOS and compared with a concurrent control group. DATA COLLECTION AND ANALYSIS: Fourteen trials were identified; eight were included in the review of which seven were randomised. All trials were assessed for quality criteria. The main studied outcomes were ovulation and pregnancy rates. Miscarriage rate, multiple pregnancy rate, and incidence of overstimulation and ovarian hyperstimulation syndrome rate were secondary outcomes. MAIN RESULTS: With the exception of multiple pregnancy rates no differences were demonstrated for any of the interventions studied but the numbers of patients who have been randomised to controlled studies at this time is insufficient to conclude that laparoscopic ovarian drilling is more effective than gonadotrophin therapy for other outcomes. REVIEWER'S CONCLUSIONS: The value of laparoscopic ovarian drilling as a primary treatment for subfertile patients with anovulation (failure to ovulate) and polycystic ovarian syndrome (PCOS) is undetermined. There is insufficient evidence to determine a difference in ovulation or pregnancy rates when compared to gonadotrophin therapy as a secondary treatment for clomiphene resistant women. Multiple pregnancy rates are reduced in those women who conceive following laparoscopic drilling. None of the studied modalities of drilling technique had any obvious advantages.

Anovulation↗
PubMed1990

Twinning in cattle: II. Genetic and environmental effects on ovulation rate in puberal heifers and postpartum cows and the effects of ovulation rate on embryonic survival.

The potential of ovulation rate before 18 to 21 mo of age in puberal heifers as an indirect selection criterion for twinning rate was considered. Heritability (h2) was .07 +/- .03 for single observations and .34 +/- .18 for the mean of 7.9 estrous cycles per heifer. Estimated repeatability (r) of ovulation rate was less than or equal to h2, indicating negligible permanent environmental effects. Expected h2 for mean ovulation rate (assuming h2 = r = .07 for single observations) for increasing numbers of estrous cycles would be as follows: 4, .23; 6., 31; 8, .38; and 10, .43. About 50% of the heifers produced no multiple ovulations, but 27% produced multiple ovulations in more than 15% of their estrous cycles. Ovulation rate varied seasonally and increased about .01 per month of age (P less than .05). Genetic correlation of mean ovulation rate with adjusted 368-d weight was low (.08 +/- .32). Ovulation rate in postpartum cows was higher (P less than .05) in fall than in spring (1.15 vs 1.08). In postpartum cows, estimated h2 = .24 +/- .13 and r = .17. Mean ovulation rate for postpartum cows was 1.12 vs 1.09 in puberal heifers, accounting in part for the higher h2. Pregnancy rate was higher (P less than .05) in multiple- than in single-ovulating cows. Effects of ovulation rate on embryonic survival were small (P greater than .05). Unilateral and bilateral multiple ovulations were not different in embryonic survival. Accuracy of ovulation rate determination by palpation per rectum was lower in multiple- than in single-ovulating postpartum cows, because some unilateral multiple corpora lutea, especially, were recorded as singles. Results suggest that use of ovulation rate in puberal heifers should permit effective indirect selection for twinning rate among yearling heifers based on individual performance and among young sires based on ovulation rate of sibs and daughters.

Animals↗
PubMed2005

Evaluation of ovulation rate and ovarian phenotype in puberal heifers from a cattle population selected for increased ovulation rate.

Long-term selection for increased ovulation rate (1984 to 2002) has resulted in a unique ovarian phenotype in the MARC Twinner cattle population. Ovulation rate and frequency of bilateral ovulations were examined by rectal palpation in 29,547 estrous cycles for 3,910 heifers (12 to 18 mo of age) in this population. Bilateral ovulations (one corpus lutuem [CL] on each ovary) were of interest because bilateral twin pregnancies result in decreased dystocia and increased calf survival. Ovulation rate increased linearly at a rate of 0.026 CL per year, and it currently averages 1.48 +/- 0.04 CL per estrous cycle. Concurrent with the increase in ovulation rate, the frequency of triplet ovulations increased from 0% to 2.3 +/- 0.8% (P < 0.001). Ovulation rate of both the right and left ovary increased equally at a rate of 0.013 CL per year, and mean ovulation rate of the right ovary remained greater than mean ovulation rate of the left ovary throughout the study (0.66 vs. 0.55 +/- 0.003 CL per estrous cycle; P < 0.001). Although correlations were low, ovulation rate of one ovary was negatively correlated (P < 0.001; r = -0.07) with ovulation rate of the same ovary in the previous estrous cycle, but positively correlated (P < 0.001; r = 0.13) with the contralateral ovary of the previous estrous cycle. The proportion of bilateral ovulations averaged 55.7 +/- 0.7%, a value greater than the predicted 49.5% (P < 0.001). In addition to dystocia and retained placenta, triplet pregnancies increase the incidence of pregnancies gestating fetuses of opposite sexes and subsequent incidence of freemartins; thus, selection pressure on ovulation rate may need to be adjusted in the MARC Twinner population. The proportion of bilateral ovulations in the population is greater than expected, and this may be an economically important trait, which will respond to selection and be beneficial for improving bovine reproductive efficiency. Understanding factors controlling the increased functional activity of the right ovary and bilateral ovulations may provide further insights into the mechanisms controlling follicle selection and methods to improve reproductive management of cattle.

Animals↗
PubMed1996

Inhibition of nitric oxide: effects on interleukin-1 beta-enhanced ovulation rate, steroid hormones, and ovarian leukocyte distribution at ovulation in the rat.

The ovulatory process resembles an inflammatory reaction with an infiltration of leukocytes, production of inflammatory mediators such as cytokines, and a general edema and hyperemia. Nitric oxide (NO), a potent vasodilator and the main mediator of macrophage tumoricidal and bacteriocidal activities, is known to participate in inflammatory reactions and has been shown to mediate the interleukin-1 beta (IL-1 beta)-directed tissue-remodeling events within the ovary. The regulation by NO of ovulation rate, leukocyte distribution, and steroid release in the rat ovary was investigated through use of a combination of in vivo and in vitro models of ovulation and a competitive inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME), of the NO synthase (NOS) enzyme. Subcutaneous L-NAME (1.5 x 10(-4) mol/kg) administration significantly reduced the in vivo ovulation rate of eCG/hCG-primed rats (L-NAME-treated: 10.6 +/- 1.8 [mean +/- SEM] oocytes per ovary [O/O], 11.0 +/- 1.2 rupture sites per ovary [RS/O]; saline-treated: 18.0 +/- 1.8 O/O, 19.4 +/- 1.1 RS/O; p < 0.01) at 20 h post-hCG. These results were reflected in vitro, where addition of L-NAME (3.5 x 10(-5) mol/L) to LH (0.1 microgram/ml)-perfused ovaries decreased ovulation rate from 8.2 +/- 1.6 to 2.7 +/- 1 ovulations per ovary (p < 0.05) and simultaneously decreased nitrite accumulation at the completion of perfusions from 16.5 +/- 1.9 to 4.1 +/- 0.5 nmol/ml (p < 0.001). The addition of L-NAME to LH+IL-1 beta (4 ng/ml)-perfused ovaries decreased ovulation rate from 15.2 +/- 2.4 to 0.8 +/- 0.8 ovulations per ovary (p < 0.001) and simultaneously decreased nitrite accumulation at 22 h from 22.8 +/- 2.2 to 1.9 +/- 0.6 nmol/ml (p < 0.001). Studies analyzing and manipulating perfusion flow rate indicated that the L-NAME effects on ovulation rate are primarily due to a reduction in flow rate resulting from inhibition of NO, which may be a consequence of the known vasoconstrictor effects of NOS inhibitors. The observed reduction of in vivo ovulation rate by NO inhibition at 20 h post-hCG was associated with a significant reduction in thecal MCA149+ neutrophils at 12 h post-hCG, the expected time of ovulation (L-NAME-treated: 98.4 +/- 9.2 cells per thecal area; saline-treated: 211.5 +/- 11.5 cells per thecal area; p < 0.001), while ED1+ monocytes/macrophages underwent similar but nonsignificant changes. Plasma (20 h post-hCG) and perfusate progesterone were not different with L-NAME treatment, while perfusate estradiol levels were markedly reduced upon addition of L-NAME, suggesting a role for NO in ovulation but not in the process of luteinization. In summary, deprivation of NO by use of the competitive inhibitor, L-NAME, led to fewer ovulations, reduced accumulation of nitrite, a decreased neutrophil count in the theca of preovulatory follicles, and reduced estradiol secretion, while progesterone release remained unaffected. The NO pathway may therefore play an important role in the regulation of ovulation and the mediation of IL-1 beta's pro-ovulatory effects. There are likely to be primarily vascular effects, but also a nonvascular component, to the NO regulation of ovulation, with both components indirectly affecting ovulatory leukocyte distribution and steroid secretion.

Animals↗
PubMed2004

Proliferating cell nuclear antigen immunoreactivity in the ovarian surface epithelium of mice of varying ages and total lifetime ovulation number following ovulation.

Everytime an oocyte is released at ovulation, the ovarian surface epithelium (OSE) is ruptured and must be restored by epithelial cell proliferation. Ovulation site closure was studied in mice of various ages along with total lifetime ovulation number to investigate the known association of these factors with the risk of epithelial ovarian cancer. Ovaries from Swiss Webster mice were collected at various time points postovulation from 3-mo virgin animals (estimated median total lifetime ovulation number, 92; n = 40 mice), 8-mo virgin animals subject to incessant ovulation (estimated median total lifetime ovulation number, 652; n = 15 mice), and 12-mo breeders (estimated median total lifetime ovulation number, 208; n = 35 mice). Diameters of ovulation sites were estimated by scanning electron microscopy. No differences were found in the rate of ovulation site closure between the groups. Sections of ovaries were analyzed using immunohistochemistry for proliferating cell nuclear antigen (PCNA). The highest density of immunoreactive cells was observed in all animal groups in the cuboidal cells around the rupture site the day after ovulation. Despite the similarity in ovulation site closure rates between groups, the total number of OSE cells that were positive for PCNA in both the 8- and 12-mo animals was significantly reduced, so the number of stained cells appeared to be insufficient to cover the ovulation site. These data suggest that other mechanisms, such as proliferation of the extraovarian mesothelium, may play a role in the re-epithelialization of the ovary.

Aging↗
PubMed1987

Hormone changes during ovulation and effects of steroid hormones on plasma gonadotropin levels and ovulation in goldfish.

Plasma hormone changes during ovulation and the effects of steroid hormones on plasma gonadotropin (GtH) levels and ovulation were studied in the female goldfish. Ovulation was induced by raising water temperature from 12 to 20 degrees. Plasma gonadotropin levels exhibited a gradual rise during the latter half of the light phase. This was then followed by a surge in GtH, showing a peak at the time of ovulation in the dark phase. After ovulation, GtH levels decreased rapidly by the next light phase. Plasma 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17 alpha,20 beta-diOH-P) and testosterone showed a peak before ovulation, and then decreased by the time of ovulation. Estradiol-17 beta (E2) showed moderate levels during the GtH surge. No marked decrease of E2 levels was observed before the commencement of the GtH surge. Administration of testosterone or E2 prior to elevating the water temperature did not inhibit the occurrence of the GtH surge and ovulation. Likewise, administration of neither 17 alpha-hydroxyprogesterone nor 17 alpha,20 beta-diOH-P affected plasma GtH levels at 20 degrees. The present study shows a clear picture of the hormone changes that occur during spontaneous ovulation in goldfish. The results of administering steroids prior to ovulation does not support the hypothesis that a decline in E2 levels triggers the GtH surge and ovulation.

Animals↗
PubMed2001

Human chorionic gonadotropin (hCG): the effect of dose on ovulation and pregnancy rate in Thoroughbred mares experiencing their first ovulation of the breeding season.

AIM: To determine the effect of hCG dose on ovulation and pregnancy rate in Thoroughbred mares experiencing their first ovulation of the breeding season. METHODS: Over 3 successive breeding seasons, a total of 101 mares were randomly assigned to 1 of 4 treatment groups (intravenous injection of either saline, 1500, 3000, or 6000 IU hCG), as they approached their first ovulation of the breeding season. Mares were bred 1 day post-injection to 1 of 11 stallions, and every other day until ovulation occurred. Data were analysed using multivariable logistic regression with correction for over-dispersion due to clustering. RESULTS: Mares treated with hCG were more likely to ovulate within 72 h of treatment than mares treated with saline (p<0.001); there was no significant difference between doses of hCG on risk of ovulation (p>0.15). Farm also had a significant impact on the risk of ovulation (p=0.027). Mares treated with hCG were more likely to be diagnosed pregnant 14 days post ovulation than saline-treated mares (p=0.081, p=0.029 and p=0.026 for the 1500, 3000 and 6000 IU doses, respectively); there was no significant difference between doses of hCG on risk of pregnancy (p>0.45). CONCLUSIONS: A single injection of hCG (1500-6000 IU) is effective at inducing ovulation in late transitional mares and increases the likelihood of pregnancy at 14 days post ovulation. This paper supports the use of hCG as an integral part of optimal broodmare management.

Journal Article↗
PubMed2000

Ovulation suppression for endometriosis.

BACKGROUND: Although the etiology of endometriosis is unknown, several theories exist, the most popular of which is retrograde menstruation. As endometriosis can only be diagnosed by laparoscopy, neither the incidence (annual occurrence) nor the prevalence (proportion of the population affected) of endometriosis is known. The association between endometriosis and infertility isn't clear in Stage I (minimal) and Stage II (mild) endometriosis. Endometriosis appears to be an estrogen dependent condition. At the time of menopause, most endometriosis becomes quiescent. This hormonal dependency prompted researchers to seek agents which would suppress ovarian activity. OBJECTIVES: To determine effectiveness of a) ovulation suppression with danazol, medroxy progesterone acetate, gestrinone, combined oral contraceptive pills and GnRH analogues versus placebo or no treatment and b) any of the above agents versus danazol, for the treatment of endometriosis explained infertility in terms of clinical pregnancy rate. SEARCH STRATEGY: The Cochrane Subfertility Review Group specialised register of controlled trials was searched. SELECTION CRITERIA: Four RCTs with five treatment arms compared an ovulation suppression agent with placebo or no treatment. Eight trials were identified comparing a suppressive agent with danazol. DATA COLLECTION AND ANALYSIS DATA EXTRACTION: A diverse search strategy was employed, including hand-search of 43 core journals from 1966 to the present, bibliographies of relevant trials, MEDLINE database, abstracts from North American and European meetings and contact with authors of relevant papers. Relevant data were extracted independently by two reviewers using the standardised data extraction sheet. Validity was assessed in terms of method of randomisation, completeness of follow-up, presence or absence of crossover and co-intervention. DATA SYNTHESIS: 2x2 tables were generated for all relevant outcomes. Odds ratios were generated using the Peto modified Mantel-Haenszel technique. Statistical heterogeneity was assessed using x2. MAIN RESULTS: The common odds ratio for pregnancy following ovulation suppression versus placebo or no treatment was 0.83 (95% CI 0.5-1.39). These data were statistically homogeneous although clinical heterogeneity was present. Their consistency in showing no treatment benefit suggests that this group of interventions is ineffective. Common odds ratio for pregnancy following all agents versus danazol was 1.20 (95% CI 0. 85-1.68). Again these data were homogeneous and suggest no significant treatment benefit in terms of pregnancy rate. REVIEWER'S CONCLUSIONS: Given the significant period of amenorrhea associated with ovulation suppression, the lack of treatment benefit demonstrated and the adverse effects commonly associated with these treatments, ovulation suppression cannot be recommended as a standard therapy for endometriosis-associated infertility.

Danazol↗
PubMed2000

Right-sided ovulation favours pregnancy more than left-sided ovulation.

The aim of this study was to evaluate whether frequency of ovulation and fertility potential of oocytes from the two ovaries differed in regularly menstruating women (1057 cycles of 856 fertile women and 1033 cycles of 258 infertile women). For both fertile and infertile women ovulation from the right ovary occurred more often than from the left ovary (55 versus 45%; P: < 0.005). In infertile women follicular phase length was similar for right- and left-sided ovulation. However, infertile women treated with intrauterine insemination (IUI) or in-vitro fertilization (IVF) showed a pregnancy rate in connection with right-sided ovulation (13%) which was higher than that of left-sided (9%). The ratio of pregnancies deriving from the right ovary per total number of pregnancies was similar in infertile and fertile women (64.6%, 73/113 and 63.4%, 361/569 respectively). The ratio of pregnancies from right-sided ovulation (approximately 64%) per total number of pregnancies was higher than that of right-sided ovulation (approximately 55%) during non-pregnant cycles (P: < 0.0001). The implantation rate in right-sided ovulation seemed to be higher than in left-sided one, since IVF data showed a lower frequency (P: = 0.03) of pre-embryo formation from right-sided ovulation than left-sided. Mid-luteal serum oestradiol and testosterone were higher (P: < 0.05) in right-sided ovulation than left-sided. Taken together, in both fertile and infertile women the fertility potential of oocytes from the right ovary surpasses that of the left ovary.

Embryo Implantation↗
PubMed1979

Intervals between multiple ovulations in PMSG-treated and untreated ewes and the relationship between ovulation and oestrus.

The timing of ovulations in 42 PMSG-treated ewes was determined by repeated endoscopy. The first ovulation occurred at a median time of 23 . 6 +/- 0 . 5 (s.e.m.) h after the onset of oestrus. The median interval between first and second ovulations was less than 1 h, and that between first and last ovulations was approximately 6 h. In 59 untreated ewes, probit regression analysis was applied to the number of ovulations which were found by endoscopy to have occurred by 23, 25 and 27 h after the onset of oestrus. The median time of first ovulation was 25 . 5 +/- 0 . 5 h after the onset of oestrus, this interval being similar in single- and twin-ovulating ewes. The median interval between twin ovulations was 1 . 2 +/- 0 . 6 h. Ovulation occurred after the end of oestrus in at least 75% of ewes.

Animals↗
PubMed1997

The period of ovulation and presence of the first polar body of ova ovulated in the house musk shrew (Suncus murinus).

The period of ovulation in mature house musk shrews was examined in a natural mating group and a superovulation group treated with gonadotropin. In the natural mating group, ovulation started 14 hr after mating in 3 of the 7 house musk shrews (42.8%), and occurred in all 5 house musk shrews by 15 hr after mating. In the superovulation group, ovulation started 13 hr after the administration of hCG in 3 of the 5 house musk shrews, and was observed in all 5 shrews by 16 hr after the administration. In the natural mating group, ovulated ova were collected from the ovarian bursa of 14 house musk shrews 14-20 hr after mating (mean, 2.2 +/- 1.0 ova) and from the oviduct of 42 animals 14-24 hr after mating (mean, 3.6 +/- 1.8 ova). Among the ova ovulated 14-16 hr after mating, both mature ova with the first polar body and immature ova without the first polar body were observed. In the superovulation group, ovulated ova were collected from the ovarian bursa of 31 house musk shrews 13-22 hr after the administration of hCG (mean, 9.7 +/- 6.8 ova), and from the oviduct of 28 animals 13-24 hr after the administration of hCG (mean, 20.0 +/- 11.7 ova). There were also mature and immature ova in the ova ovulated 13-16 hr after the administration of hCG. The time when ova ceased to be recovered from the ovarian bursa roughly coincided with the time when new corpora lutea ceased to be found in the ovaries. These findings suggested that the period of ovulation of house musk shrews was 14-20 hr after mating in the natural mating group and 13-22 hr after the administration of hCG in the superovulation group. Both the natural mating group and superovulation group ovulated both mature ova with the first polar body and immature ova without the first polar body.

Animals↗
PubMed1997

Studies of mice lacking plasminogen activator gene function suggest that plasmin production prior to ovulation exceeds the amount needed for optimal ovulation efficiency.

Many studies suggest that the plasminogen activator (PA) system plays a role in the proteolytic degradation of the follicle wall at the time of ovulation. Consistently, the ovulation efficiency is reduced by 26% in mice where both physiological PA genes have been inactivated. To reveal the mechanism behind reduced ovulation efficiency in PA-deficient mice and its effect on ovarian proteolysis. we have studied the regulation of plasmin activity in the ovaries of 25-day-old wild-type mice and mice with deficient PA gene function during gonadotropin-induced ovulation. In wild-type mice the plasmin activity was low in ovarian extracts from mice treated with pregnant mare's serum gonadotropin. However, this activity was increased between 2-8 h after an ovulatory dose of human choriogonadotropins. In mice lacking either tissue-type PA (tPA) or PA inhibitor type 1 (PAI-1) the plasmin activity levels prior to ovulation were similar to wild-type mice, while extracts prepared from urokinase-type PA (uPA) deficient mice had 10% or less of the plasmin activity. This indicates that most of the plasmin activity in the mouse ovary is generated by uPA. In addition, as the ovulation efficiency is impaired in tPA/uPA-deficient mice but appears normal in uPA-deficient mice, our data indicates that the amount of plasmin generated by PAs prior to ovulation in wild-type mice greatly exceeds the amount required for efficient ovulation.

Animals↗
PubMed1998

Close synchrony of ovulation in superstimulated heifers that have a downregulated anterior pituitary gland and are induced to ovulate with exogenous LH.

The synchrony of ovulation was examined in superstimulated heifers that had a downregulated pituitary gland and which were induced to ovulate by injection of exogenous LH. The pituitary was downregulated and desensitized to GnRH by treatment with the GnRH agonist deslorelin. Nulliparous heifers (3.5 yr old) at random stages of the estrous cycle were assigned to 1 of 3 groups, and on Day -7 received the following treatments: Group 1 (control, n = 8), 1 norgestomet ear implant; Group 2 (GnRH agonist, n = 8); Group 3 (GnRH agonist-LH protocol, n = 8), 2 deslorelin ear implants. Ovarian follicle growth in all heifers was superstimulated with twice-daily intramuscular injections of FSH (Folltropin-V): Day O, 40 mg (80 mg total dose); Day 1, 30 mg; Day 2; 20 mg; Day 3, 10 mg. On Day 2, all heifers were given a luteolytic dose of PGF (7 A.M.), Norgestomet implants were removed from heifers in Group 1 (6 P.M.). Heifers in Group 3 were given an injection of 25 mg, i.m. porcine LH (Lutropin) on Day 4 (4 P.M.). Ovarian follicle status was monitored at 8-h intervals from Day 3 (8 A.M.) to Day 6 (4 P.M.) using an Aloka Echo Camera and 7.5 MHz transducer. Heifers in Groups 2 and 3 exhibited estrus earlier (P < 0.05) than heifers in Group 1. Heifers in Group 2 did not have a preovulatory LH surge and they did not ovulate. Individual control heifers in Group 1 ovulated between 12 A.M. on Day 5 and 8 A.M. on Day 6. Heifers with deslorelin implants and injected with LH in Group 3 ovulated between 4 P.M. on Day 5 and 8 A.M. on Day 6. It was confirmed that superstimulated heifers with GnRH agonist implants can be induced to ovulate with LH. It was also demonstrated that ovulation is closely synchronized after injection of LH. Thus, a single, fixed-time insemination schedule could be used in a GnRH agonist-LH superovulation protocol, with significant practical and economic advantages for superovulation and embryo transfer programs.

Animals↗
PubMed1979

Oestrus, time of ovulation, ovulation rate and conception rate in progestagen-treated ewes given Gn-RH, Gn-TH analogues and gonadotrophins.

The influence of Gn-RH, hCG and a PMSG-hCG mixture (PG600) on the time of ovulation, ovulation rate and on the occurrence of oestrus in ewes treated with progestagen-impregnated sponges for 12 days examined. The effects of Gn-RH analogues on plasma LH, oestrus, ovulation and conception rate were also investigated. Six separate experiments were carried out. When 50 micrograms Gn-RH were given 24 h after sponge removal ovulation occurred in 44--46% of ewes within 24 h and in all ewes by 34 h. Gn-RH was a more potent ovulation synchronizer than hCG. Both hCG and PG600 reduced the incidence of overt oestrus. Gn-RH also had this effect in ewes treated during February and May but not in August and September. Gn-RH analogues given 2 days before sponge removal significantly increased ovulation rate. The display of oestrus was not affected in ewes treated 2 days before sponge removal but was suppressed in 43-69% of ewes treated with an analogue at the time of sponge removal. Ovulation occurred in 50-62% of ewes within 30-35 h of injection of Gn-RH analogues, regardless of the time of their administration. The release of LH in response to one analogue was not influenced by the presence of the progestagen-impregnated sponge in the vagina. When given a Gn-RH analogue 2 days before sponge removal or at the time of sponge removal 63 and 62% of mated ewes became pregnant compared with 70% of control ewes.

Animals↗
PubMed2000

Comparison of plasma FSH concentration in boars and gilts from lines selected for ovulation rate and embryonal survival, and litter size and estimation of (co)variance components for FSH and ovulation rate.

The objective of this research was to determine whether plasma concentration of FSH was genetically correlated with ovulation rate and thus was a useful trait for indirect selection. Blood samples were collected from 619 animals from five lines of pigs. Line I was selected for increased index of ovulation rate and embryonal survival, and Line C was its randomly selected control. Pigs sampled from Lines I and C were from generations 12 and 13. Pigs from three additional lines that were derived from eighth-generation pigs of Lines I and C also were used. These lines were Line C2, a randomly selected control derived from Line C, Line COL, derived from Line C, and Line IOL, derived from Line I; each of these lines was selected an additional five generations for increased ovulation rate and increased litter size. A single blood sample was collected from each pig between 46 to 63 (d 58), 86 to 98 (d 90), 110 to 133 (d 124), and 147 to 153 (d 150) d of age. The heritability of ovulation rate was .28 and heritabilities of plasma concentration of FSH at d 58, 90, 124, and 150 were .41, .25, .12, and 0, respectively. Genetic correlations between ovulation rate and d-58, d-90, and d-124 plasma concentration of FSH were .31, .23, and 0, respectively. Line I gilts had greater estimated breeding values for plasma concentration of FSH at d 58 and 90 than Line C gilts (P < .01). Line COL gilts had greater estimated breeding values for plasma concentration of FSH at d 58 than Line C2 gilts (P < .01). Line I boars had greater estimated breeding values for plasma concentration of FSH at d 90 than Line C boars (P < .05). Even though genetic correlations were low, selection for increased plasma concentration of FSH was estimated to be 93% as effective in changing ovulation rate as direct selection because selection for FSH can be practiced in both sexes. Thus, selection for increased plasma concentration of FSH seems to be a practical method for increasing ovulation rate in pig breeding programs without using laparoscopy.

Animals↗
PubMed1989

Ovulation prediction by monitoring salivary and vaginal electrical resistance with the PEAK Ovulation Predictor.

We investigated the ability of the PEAK Ovulation Predictor to predict the expected date of ovulation in 21 infertile, spontaneously ovulating women. A nonsignificant correlation (R = 0.15; P = .51) existed between the predicted date of ovulation and the day of the serum LH peak. A moderately strong correlation (R = 0.61; P less than .01) was observed between the day of the salivary electrical resistance peak and that of the serum LH peak. However, the serum LH peak occurred between 4-9 days after an identified peak in salivary electrical resistance. Twice-daily urine LH testing correlated strongly with both the serum LH peak (R = 0.93; P = .0001) and the ultrasound-detected day of ovulation (R = 0.81; P = .0001). A statistically significant peak in the mean salivary or vaginal electrical resistance on a particular day relative to the day of the serum LH peak could not be demonstrated. When identified, the nadir in vaginal electrical resistance occurred no earlier than 2 days before the serum LH peak and thus may mark the endpoint of the fertile period for natural family planning methods. We conclude that, whereas the PEAK Ovulation Predictor is of little value in accurately predicting ovulation, measurements of salivary and vaginal electrical resistance may be helpful in timing inseminations. However, for detection of the serum LH surge, twice-daily urine LH testing demonstrated a stronger correlation and narrower frequency distribution than did those determinations based on electrical resistance.

Adult↗
PubMed1983

Relationship between number of induced ovulations in the prepubertal gilt to the level of progesterone and to the number of spontaneous postpubertal ovulations.

A series of experiments were conducted to investigate the relationship between the number of corpora lutea (CL) and concentration of progesterone (P4) on different days after induced and spontaneous ovulation of gilts of different ages. Possible relationship between the number of ovulations after injection of gonadotropin into the prepubertal gilt and the number at a second induced ovulation and finally the number of postpubertal, spontaneous ovulations, was also studied. Number of CL was related (r = .75 to .95, P less than .01) to levels of P4 on d 3 to 10 after induced ovulation of prepubertal gilts of 105 to 180 d of age. Relationship between the number of CL and level of P4 in cyclic gilts ranged from r = .28 to .67 with the highest relationship at d 4 to 9. Number of CL induced at 135 d of age was correlated (r = .67 to .91, P less than .01) with number of CL induced at 195 d. There were correlations (r = .75 to .99, P less than .01) between levels of P4 and number of CL on d 7 to 9 after induction of ovulation of gilts of 135 and 195 d of age with either pregnant mare's serum gonadotropin (PMSG) followed in 96 h by human chorionic gonadotropin (hCG) or estradiol benzoate (EB) followed in 72 h by hCG. There was a correlation (r = .84, P less than .001) between number of CL at the first spontaneous postpubertal estrus and number of CL at third estrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗