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PubMed1989

Season determines timing of first ovulation in rhesus monkeys (Macaca mulatta) housed outdoors.

In order to determine the relative importance of age and season on the occurrence of first ovulation in rhesus monkeys, the timing of puberty in spring-born females (Group S, N = 13) was compared to that of fall (N = 3) and winter-born (N = 5) females (Group W). All females were housed outdoors and were studied from 12 months of age through first ovulation. Menarche occurred at a similar age but significantly earlier in the year for Group W (31.2 +/- 0.7 months; 25 August +/- 19.5 days) than for Group S females (31.2 +/- 0.7 months; 14 November +/- 17.1 days). First ovulation, as assessed from twice weekly serum progesterone determinations, occurred exclusively in the fall or winter in a bimodal age distribution for all females. For Group W females, 6/8 ovulated during the 3rd year at 35.8 +/- 0.7 months while 2/8 ovulated during the 4th year at 45.3 +/- 0.1 months. In contrast, only 3/13 Group S females ovulated during the 3rd year and at a significantly younger age of 31.4 +/- 0.4 months compared to Group W. The remaining Group S females (10/13) ovulated the following autumn at 43.2 +/- 0.2 months, significantly younger than the later ovulating Group W females. In addition to this pattern of first ovulation, serum concentrations of prolactin varied seasonally, rather than with age, in both groups of females with higher levels in the summer and low levels in the winter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Husbandry↗
PubMed1998

Changes in circulating and ovarian concentrations of bioactive tumour necrosis factor alpha during the first ovulation at puberty in rats and in gonadotrophin-treated immature rats.

Tumour necrosis factor alpha (TNF-alpha) concentrations were measured during periods of controlled and natural follicular development and ovulation in rat ovaries. Concentrations of bioactive TNF-alpha were determined in the ovaries and sera of rats during puberty (the period of vaginal opening and the first ovulation) and in immature rats after gonadotrophin treatment. Ovaries and sera were collected from 33-, 35-, 37-, 39-, 41- and 43-day-old rats (n = 6 or 7 per group); vaginal opening occurs on day 35. The presence of ovarian follicles and corpora lutea or ova in the oviducts was assessed. For gonadotrophin treatment, a single subcutaneous injection of 5 iu equine chorionic gonadotrophin (eCG) was administered at 08:00 h to 28-day-old rats to stimulate follicular development. A single subcutaneous injection of 10 iu human chorionic gonadotrophin (hCG) was administered 48 h later to induce ovulation. Ovaries and sera from three to six animals per group were collected 0, 3, 24, 48, 51, 54, 57, 60 and 72 h after injection of eCG. At puberty, ovarian concentrations of TNF-alpha were highest (approximately 1.1 fg micrograms-1 ovarian protein) before vaginal opening and the first ovulation. After vaginal opening and ovulation at day 37, ovarian concentrations of TNF-alpha were markedly reduced (0.091 fg microgram-1 ovarian protein) and remained low up to day 43. Serum concentrations of TNF-alpha remained low throughout the period of vaginal opening and the first ovulation (8-32 pg ml-1). In 43-day-old rats serum concentrations of TNF-alpha increased (105 pg ml-1). In the immature ovaries of 28-day-old rats TNF-alpha concentrations were highest before injection of eCG (approximately 1.2 fg micrograms-1 ovarian protein) and decreased to approximately 0.4 fg microgram-1 protein 3 h after injection. TNF-alpha concentrations decreased further 24 h after eCG injection (< 0.1 fg microgram-1 protein) and remained low until 48 h after eCG injection. Serum concentrations of TNF-alpha did not change during the 48 h period after injection of eCG. hCG was administered 48 h after eCG, and ovarian and serum TNF-alpha concentrations increased transiently. Serum TNF-alpha concentrations increased 3 h after hCG and remained elevated until 9 h after injection, after which concentrations decreased. Ovarian concentrations of TNF-alpha increased 6 h after hCG, peaked (approximately 0.5 fg microgram-1 protein), and then declined. These results indicate that during puberty and the first ovulation, circulating and ovarian TNF-alpha concentrations change. In addition, exogenous gonadotrophins alter circulating and ovarian TNF-alpha concentrations. These data suggest that TNF-alpha has a role in follicular development and ovulation during puberty and in immature rats treated with gonadotrophins to induce ovulation.

Aging↗
PubMed2001

Induced ovulation, mating success and embryonic development in the stripe-faced dunnart, Sminthopsis macroura.

Induced ovulation resulting in normal embryos is rare in marsupials. In this study natural and induced ovulations were compared in mature Sminthopsis macroura (n = 122). Comparison of maturation of preovulatory oocytes by ovarian histology and examination of oocytes removed from developing follicles in 12 ovaries of 23 animals receiving 0.058 iu equine serum gonadotrophin (eSG) g(-1) with ovaries of 12 animals undergoing natural cycles showed that oocyte maturation was significantly more irregular when it was induced (P < 0.001). Postovulatory stages were examined by estimating the number of eggs ovulated from ovarian histology, and by counting oviduct and uterine contents recovered after ovulation. S. macroura receiving 0.087 iu eSG g(-1) (n = 34), administered as one (n = 17) or two (n = 17) injections, were significantly (P < 0.05) more likely to ovulate (74%), mate (80%) and have conceptuses (66%) than were animals receiving 0.058 iu eSG g(-1) (12, 53 and 0%, respectively) (n = 17), and the values were similar to those in animals (n = 36) undergoing natural cycles (100, 81 and 56%, respectively). Induced ovulation using 0.087 iu eSG g(-1) yielded significantly (P < 0.05) more oocytes per ovary (20.8 +/- 8.5; combined data) than did ovulation in animals undergoing natural cycles (13.7 +/- 3.2) (ANOVA, t test). The responses of animals induced in different phases of the oestrous cycle with 0.087 iu eSG g(-1) were not significantly different (ANOVA) with respect to the number of corpora lutea per ovary, conceptuses per animal or days to ovulation after injection. However, the proportion of females that responded after receiving 0.058 iu eSG g(-1) in the luteal phase was significantly different from that in animals treated with the same dose in the intermediate phase (P < 0.01) and in non-cyclic females treated with 0.058 iu eSG g(-1) (P < 0.02). The main benefits of the treatment were that normal embryos resulted and that 70-78% of non-cyclic animals could be induced to ovulate.

Anestrus↗
PubMed1975

Gonadotrophin and steroid levels around the time of first ovulation in the rat.

Luteinizing hormone, FSH, prolactin, oestradiol and progesterone concentrations were measured by radioimmunoassay in the blood of female rats from 7 days before the first ovulation (the day of first ovulation is designated day 0) until the day after the second ovulation. Serum LH concentrations varied between 29 and 59 ng NIAMDD-rat-LH RP-1/ml from days -7 to -2. On the day preceding first ovulation (day -1) a steep increase in serum LH was found between 13.00 h and 15.00 h reaching a maximal value of 2100 ng/ml at 17.00 h. Thereafter LH levels decreased to undetectable values (less than 15 ng/ml). Serum FSH concentrations from days -7 to -2 varied between 108-154 ng NIAMDD-rat-FSH RP-1/ml; increased concentrations were found on the afternoon of day -1 and on the morning thereafter (first oestrus) with a maximal value of 1150 ng/ml at 19.00 h on day -1. On the day preceding the second ovulation (day +4) LH and FSH peaks were again found. Prolactin concentrations on the days preceding first ovulation were generally low. A small rise was found nearing first ovulation (12-7 ng/ml, day -6; 23-9 ng/ml, day -2). On day -1 a peak (118 ng/ml) was found at 15.00 h, similar to that found on day +4 in adult pro-oestrous rats. Plasma progesterone concentrations also reached a peak value (50 ng/ml) on day -1, at 17.00 h, preceded by concentrations between 3-5 ng/ml from days -6 to -2. Progesterone concentrations after the first ovulation showed a pattern characteristic of the adult cycle. Plasma oestradiol levels were un-etectable (less than 10 pg/ml) from days -6 to -2; a clearly increased oestradiol concentration was found on day -1, reaching a value of 98 pg/ml. One and two days before the second ovulation, oestradiol levels rose again. The differences and similarities between pubertal and adult pro-oestrous hormone peaks are discussed.

Animals↗
PubMed1978

Plasma oestradiol and delayed ovulation after administration of sodium pentobarbitone to pro-oestrous 5 day cyclic rats.

Injection of sodium pentobarbitone (Nembutal) into rats between 12.00 and 13.00 h on the day of pro-oestrus was fully effective in blocking the expected ovulation. In 75% of the rats, ovulation of the present generation of large follicles occurred 24 h later (delayed ovulation). Injection of Nembutal between 12.00 and 13.00 h on the day of pro-oestrus and at the same time on the subsequent day was fully effective in blocking the ovulation twice: in only two rats out of 13 did ovulation of the present generation of follicles still occur. When unilateral ovariectomy was performed immediately after injection of a single dose of Nembutal into pro-oestrous rats, delayed ovulation was significantly inhibited. However, after inhibition of ovulation by either two injections of Nembutal or one injection and unilateral ovariectomy, delayed ovulation could be induced by treatment with a small dose of oestradiol benzoate during the Nembutal-induced anaesthesia. It thus seemed that delayed ovulation failed because of disruption of oestrogen production after administration of Nembutal. The concentration of oestradiol-17beta in the plasma of Nembutal-treated pro-oestrous rats decreased rapidly during the 24 h after treatment. It is concluded that this decrease in the concentration of oestradiol is due to the inherent ageing of preovulatory follicles manifesting itself when exposure to the ovulatory surge of LH is inhibited.

Animals↗
PubMed1982

Ovarian follicular development leading to first ovulation and accompanying gonadotrophin levels as studied in the unilaterally ovariectomized rat.

Ovarian follicular development was studied in the rat during a 15-day period preceding first ovulation. Ovaries were obtained by unilateral ovariectomy performed at various ages and the rats were allowed to live until the day after first ovulation. The timing of this ovulation was compared with that in unoperated, paired control rats of the same age. For estimation of gonadotrophin levels, blood was taken from the paired control rats at the time when experimental rats were unilaterally ovariectomized. There was no evidence that unilateral ovariectomy had any influence on the timing of first ovulation. Therefore the ovaries obtained could be dated in relation to first ovulation, and follicular growth during the final prepubertal period could thus be studied in a genuine developmental sequence. Results revealed that follicular growth leading to first ovulation starts at +/- 8 days before this ovulation; follicular processes taking place are comparable to those found during the adult 5-day cycle but proceed more slowly. Gonadotrophin concentrations accompanying the follicular dynamics and measured at 11.00 h, showed a clear tendency for FSH concentrations to decrease with increasing age, i.e. approaching first ovulation. Concentrations of LH did not show a definite pattern and were generally low, although in some individual rats relatively high LH values ( greater than 100 micrograms/l) were found in the period of 5-3 days before first ovulation.

Animals↗
PubMed1995

Recombinant FSH (Org32489) induces follicle growth and ovulation in the adult cyclic rat.

The effects of a single injection of recombinant human FSH (rhFSH; Org32489) on ovulation rate and timing and on antral follicle growth were studied in adult 5-day cyclic rats. Rats injected at 1700 h on dioestrus-2 with a dose of 10 IU rhFSH showed, on average, no increase in ovulation rate on the day of expected oestrus. However, an additional, precocious ovulation resulting in a normal number of corpora lutea (13.3 +/- 0.4, n = 6) was found to take place on the night after injection, i.e. dioestrus-3. No mating behaviour, as shown by the absence of vaginal plugs the next morning, was observed at this ovulation. Follicle counts showed a loss of large antral follicles due to ovulation and increased numbers of healthy small antral follicles at 17 and 41 h after injection, indicating a decrease of atresia of growing follicles as well as additional recruitment of new antral follicles. The endogenous serum FSH concentration on the subsequent day of oestrus (65 h after the rhFSH injection) as well as recruitment of small antral follicles were lower in the rhFSH-treated rats than in saline-treated controls. The ovulation at oestrus, 48 h after the precocious, rhFSH-induced ovulation showed large differences in the number of oocytes between the rats in one treatment group. Similar results in terms of immediate ovulation induction were obtained by using a highly purified human urinary FSH preparation (i.e. metrodin). Furthermore, the direct induction of ovulation by rhFSH or metrodin could not be prevented by the injection of an LHRH antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Ovulation rate and twinning rate in cattle: heritabilities and genetic correlation.

Repeated measures of ovulation rate on puberal heifers should be an effective way to select for increased twinning rate. A reliable estimate of the genetic correlation between ovulation and twinning rates is needed to implement such selection and to predict its efficiency. Restricted maximum likelihood was used to estimate genetic correlations from subsets of data collected from the twinning project at the Roman L. Hruska U.S. Meat Animal Research Center. The animal model included numerator relationships among the animals and fixed effects of year-season of measurement, age at measurement, and birth group. Genetic correlations between averages of ovulation rates for three, four, five, six, seven, and eight estrous cycles and the occurrence of twins were, respectively, .62, .76, 1.00, 1.00, 1.00, and .98 based on observations on 200 to 325 puberal heifers. Corresponding phenotypic correlations ranged from .06 to .26. Genetic correlations between ovulation rate in a single estrous cycle and occurrence of twins were .38, .98, and .98, respectively, for 323, 430, and 283 cows with ovulation rate measured after measurement of twinning, in the same season as measurement of twinning, and more than 1 yr before measurement of twinning. Phenotypic correlations were .00, .07, and .00. Genetic and phenotypic correlations among ovulation rates at six consecutive estrous cycles averaged, respectively, .66 and .12 for 610 heifers. Heritabilities for ovulation rates in individual cycles averaged .16. No evidence of negative environmental covariance between ovulation rates in adjacent cycles was found. These results support the approach of indirectly selecting for twinning rate by measuring ovulation rates in estrous cycles of puberal heifers.

Animals↗
PubMed2001

Intervals from norgestomet withdrawal and injection of equine chorionic gonadotropin or P.G. 600 to estrus and ovulation in ewes.

Synchronization of estrus and ovulation is essential for AI of ewes during a predetermined time frame, and progestogen-eCG treatments are typically used to prepare the ewes. However, eCG is not readily available in the United States, but P.G. 600 (400 IU of eCG and 200 IU of hCG) is available. Thus, we conducted a study to determine the effects of eCG and P.G. 600 on the timing of estrus and ovulation after progestogen withdrawal. Ewes were assigned to two replicates of an experiment with the following treatments: 1) 3-mg norgestomet implant (i.e., one-half of a Syncro-Mate-B [SMB] implant) for 10 d, plus 2 mL of saline i.m. at SMB removal (n = 11); 2) 3-mg SMB implant for 10 d, plus 400 IU of eCG i.m. at SMB removal (n = 13); and 3) 3-mg SMB implant for 10 d, plus P.G. 600 i.m. at implant removal (n = 9). On d 6 after SMB insertion, PGF2alpha was used to induce luteolysis. Beginning 12 h after implant removal, vasectomized rams were used at 12-h intervals to check for estrus. When a ewe was detected in estrus, each ovary was evaluated ultrasonically. Ovaries were evaluated again 16 h later and then at 8-h intervals until ovulation. Treatment altered the interval from implant removal to estrus (less [P < 0.05] in SMB + eCG than in the other two groups) and to ovulation (greatest [P < 0.05] in SMB). However, the treatment x replicate interaction was significant for the intervals from implant removal to estrus (P < 0.03) and from implant removal to ovulation (P < 0.05). An inconsistent response in the SMB-treated ewes seemed to be primarily responsible for the interaction. The intervals to estrus and to ovulation for the SMB-treated ewes were shorter (P < 0.05) in Replicate 1 than in Replicate 2. Also, both intervals seemed to be less consistent between replicates for the SMB + P.G. 600- than for the SMB + eCG-treated ewes; that is, eCG seemed to increase the predictability of the intervals to estrus and to ovulation. Neither the main effects of treatment and replicate nor their interaction were significant for the interval from estrus to ovulation (38.4 /- 3.3 h), size of the ovulatory follicle (7.7 +/- 0.8 mm), or ovulation rate (1.6 +/- 0.2). We concluded from this experiment that eCG is a better choice than P.G. 600 as the gonadotropin to use at the time of progestogen withdrawal to prepare ewes for AI during a predetermined interval.

Animals↗
PubMed2004

Effect of addition of a progesterone intravaginal insert to a timed insemination protocol using estradiol cypionate on ovulation rate, pregnancy rate, and late embryonic loss in lactating dairy cows.

The objectives of this study were to determine the effects of incorporating a progesterone intravaginal insert (CIDR) between the day of GnRH and PGF2alpha treatments of a timed AI protocol using estradiol cypionate (ECP) to synchronize ovulation on display of estrus, ovulation rate, pregnancy rate, and late embryonic loss in lactating cows. Holstein cows, 227 from Site 1 and 458 from Site 2, were presynchronized with two injections of PGF2alpha on study d 0 and 14, and subjected to a timed AI protocol (100 mixrog of GnRH on study d 28, 25 mg of PGF2alpha on study d 35, 1 mg of ECP on study d 36, and timed AI on study d 38) with or without a CIDR insert. Blood was collected on study d 14 and 28 for progesterone measurements to determine cyclicity. Ovaries were scanned on d 35, 37, and 42, and pregnancy diagnosed on d 65 and 79, which corresponded to 27 and 41 d after AI. Cows receiving a CIDR had similar rates of detected estrus (77.2 vs. 73.8%), ovulation (85.6 vs. 86.6%), and pregnancy at 27 (35.8 vs. 38.8%) and 41 d (29.3 vs. 32.3%) after AI, and late embryonic loss between 27 and 41 d after AI (18.3 vs. 16.8%) compared with control cows. The CIDR eliminated cows in estrus before the last PGF2alpha injection and decreased (P < 0.001) the proportion of cows bearing a corpus luteum (CL) at the last PGF2alpha injection because of less ovulation in response to the GnRH and greater spontaneous CL regression. Cyclic cows had greater (P = 0.03) pregnancy rates than anovulatory cows at 41 d after AI (33.8 vs. 20.4%) because of decreased (P = 0.06) late embryonic loss (16.0 vs. 30.3%). The ovulatory follicle was larger (P < 0.001) in cows in estrus, and a greater proportion of cows with follicles > or = 15 mm displayed estrus (P < 0.001) and ovulated (P = 0.05) compared with cows with follicles <15 mm. Pregnancy rates were greater (P < 0.001) for cows displaying estrus, which were related to the greater (P < 0.001) ovulation rate and decreased (P = 0.08) late embryonic loss for cows in estrus at AI. Cows that were cyclic and responded to the presynchronization protocol (high progesterone at GnRH and CL at PGF2alpha) had the highest pregnancy rates. Incorporation of a CIDR insert into a presynchronized timed AI protocol using ECP to induce estrus and ovulation did not improve pregnancy rates in lactating dairy cows. Improvements in pregnancy rates in cows treated with ECP to induce ovulation in a timed AI protocol are expected when more cows display estrus, thereby increasing ovulation rate.

Abortion, Veterinary↗
PubMed1989

Integration of ovulation rate, potential embryonic viability and uterine capacity into a model of litter size in swine.

A mathematical model of litter size in swine was developed from ovulation rate, potential embryonic viability and uterine capacity. The model assumed that ovulation rate was reduced to potentially viable embryos by factors innate to the ovum and embryo. Potentially viable embryos then could be further reduced to uterine capacity, the maximum number of fetuses that a female can carry to term. Consequently, litter size can be no greater than either ovulation rate or uterine capacity. Means and variances of ovulation rate and potential embryonic viability used in the model were based on experimental results. The mean and variance of uterine capacity were varied until the simulated mean and variance of litter size were equal to experimental results. Simulated results of relationships among ovulation rate, embryo survival and litter size were similar to observed experimental relationships. Heritabilities of simulated litter size and embryo survival were similar to literature values when the heritability of ovulation rate was set at .25 and the heritability of uterine capacity was set at either .15 or .20. Litter size was simulated for 25 combinations of average ovulation rate and uterine capacity to develop equations relating mean ovulation rate and uterine capacity to litter size, embryo survival and correlations among them. Results suggest that changing either ovulation rate or uterine capacity independently will not result in large changes in litter size. Consequently, the model suggests that a single gene, hormonal manipulation or nutritional change will not result in large increases in litter size and that combinations of factors will be needed to increase litter size.

Algorithms↗
PubMed2006

Endocrine alterations associated with extended time interval between estrus and ovulation in high-yield dairy cows.

Short fertile half-lives of the male and female gametes in the female tract necessitate accurate timing of artificial insemination. We examined the possible association between extension of the estrus to ovulation (E-O) interval and alterations in concentrations of estradiol, progesterone, and the preovulatory LH surge before estrus and ovulation. High-yielding Holstein cows (n = 74 from a total of 106) were synchronized and were examined around the time of the subsequent estrus. They were observed continuously for estrual behavior. Blood samples were collected before and after estrus, and ultrasound checks for ovulation were made every 4 h. About three-quarters of the cows exhibited short (but normal) E-O intervals of 22 to 25 h (25%) or normal intervals of 25 to 30 h (47%); 17% of them displayed a long (but normal) E-O interval of 31 to 35 h, and about 10% exhibited a very long E-O interval of 35 to 50 h. Extended E-O interval comprised estrus-to-LH surge and LH surge-to-ovulation intervals that were both longer than normal. Pronounced changes in hormonal concentrations were noted before ovulation in the very long E-O interval group of cows: progesterone and estradiol concentrations were reduced, and the preovulatory LH peak surge was markedly less than in the other 3 groups. Postovulation progesterone concentrations during the midluteal phase were lesser in the very long and the long E-O interval groups compared with those in the short and normal interval groups. Season, parity, milk yield, and body condition did not affect the estrus to LH surge, LH surge to ovulation, and E-O intervals. The results indicate an association between preovulatory-reduced estradiol concentrations and a small preovulatory LH surge, on the one hand, and an extended E-O interval, on the other hand. Delayed ovulation could cause nonoptimal timing of AI, a less than normal preovulatory LH surge that may be associated with suboptimal maturation of the oocyte before ovulation, or reduced progesterone concentrations before and after ovulation. All may be factors associated with poor fertility in cows with a very long E-O interval.

Animals↗
PubMed2003

Polycystic ovary syndrome and ovulation induction.

Polycystic ovary syndrome (PCOS) is likely the most common cause of anovulatory infertility. Although many options are available for ovulation induction in these patients, there is currently no evidence-based algorithm to guide the initial and subsequent choices of ovulation induction methods. In obese women with PCOS, mild to moderate weight loss results in improvement of ovulatory dysfunction, and should be advocated at the onset of the evaluation. Clomiphene citrate is currently the 1st line medical therapy for ovulation induction. Glucocorticoids do not result in consistent ovulation and have significant side effects. Exogenous pulsatile GnRH treatment has low ovulation and pregnancy rates with a high risk of miscarriage. The most commonly used medical agents for ovulation induction in clomiphene-resistant women with PCOS are parenteral gonadotropins. Various gonadotropin preparations and different protocols are available; however the risk of multiple pregnancy and ovarian hyperstimulation is high with gonadotropin therapy. The frequent association between PCOS and insulin resistance has prompted recent studies on the effect of insulin-sensitizing agents on spontaneous and as an adjuvant to conventional ovulation induction therapies. Overall, the improvement in ovulation with insulin sensitizing drugs is modest, and unresolved issues such as variability in ovarian response remain to be addressed in future studies. Nevertheless, these agents may be beneficial in a subset of PCOS patients. Surgical ovulation induction methods such as ovarian diathermy have been reported to be moderately effective. However, due to the inherent associated risks and unknown effect on long-term reproductive potential, this modality should be reserved for patients who are clomiphene-resistant and unable or unwilling to proceed to gonadotropin therapy.

Female↗
PubMed1987

Natural family planning indicators of ovulation.

Indirect evidence of the occurrence of ovulation, which is generally accepted, is an increase in plasma or serum progesterone. Pelvic ultrasonography can estimate the probable time of ovulation within 12 h. There is a close association between the rise in progesterone, luteinizing hormone (LH) and oestrogen peaks and ovulation. A WHO study reported that ovulation occurred at a median time of 8 h after the rise in plasma progesterone, 15 h after the LH peak and 24 h after the oestrogen peak. The basal body temperature (BBT) method is the most effective in determining the premenstrual infertile period, but it is unreliable for an accurate determination of ovulation and the postmenstrual infertile period. Nor is BBT an effective method of predicting ovulation during postpartum lactational amenorrhoea. Therefore, BBT is usually used as a secondary indicator of ovulation and is combined with more reliable indicators. Observed changes in cervical mucus patterns can be used to define the probable fertile period, although this method produces a wide range of days. The peak mucus symptom is closely correlated with ovulation. Mucus symptoms can be used as a guide for the timing of blood or urine samples for estimation of LH, oestrogen and progesterone or their metabolites. Symptothermal methods incorporate other symptoms such as cervical changes, intermenstrual pain, breast tenderness and backaches, but these are secondary signs of ovulation and are recommended to be used in conjunction with mucus and BBT.

Body Temperature↗
PubMed1987

Exogenous hormone regimens to utilize successfully mares in dioestrus (days 2-14 after ovulation) as embryo transfer recipients.

Two hormone regimens were utilized for recipient mares which were 2-14 days after ovulation at the time of non-surgical embryo transfer. In Exp. I, 20 embryos were transferred non-surgically into recipient mares which had been given 22 mg altrenogest daily starting the day of recipient ovulation. Higher (P less than 0.05) pregnancy rates (50% vs 0%) were obtained in mares which were 2-6 days after ovulation at the time of transfer compared with mares which were 7-12 days after ovulation. In Exp. II, on the day the donor mare ovulated (Day 0), 10 mg PGF-2 alpha were given to the recipient mare at 0 h, 20 mg oestradiol cypionate at 12, 24 and 36 h, 500 mg progesterone in oil at 48 h and then 22 mg altrenogest at 60, 72 and 96 h. Altrenogest (22 mg/day) was continued until Day 28 (fetal heart beat). The pregnancy rate (58% vs 10%) was higher (P less than 0.05) for the 12 recipient mares which were 10-14 days after ovulation than for the 10 mares that were 5-8 days after ovulation when treatment began. Early embryonic loss was detected in 4/8 pregnant recipient mares between Days 21 and 28 of gestation. We suggest that mares which are 2-14 days after ovulation and not in ovulation synchrony with the donor may be used as embryo transfer recipients; mares which are in early dioestrus can be given altrenogest while those in mid- to late dioestrus can be placed on the more complex hormone regimen.

Animals↗
PubMed1984

[Ovulation prediction in cattle by rapid measurement of plasma LH and by laparoscopic observation].

The last hours of intrafollicular maturation are important to preserve the potential of oocytes for fertilization and development. To collect mature oocytes it is consequently essential to predict accurately the time of ovulation. Therefore we have modified a regular and specific plasma LH radioimmunoassay to a convenient assay providing reliable results within four to five hours. Using this technique we have been able to detect the LH peak with a delay small enough to predict the moment of ovulation; then we have been able to observe and photograph ovulation. The antigen-antibody reaction takes place during a two hour incubation at 37 degrees C. The immune complex is precipitated by addition of a rabbit anti-gamma-globulin and incubation at 22 degrees C for 30 minutes. The variation between fast and regular assays is lower than 15%. From a study of 25 cycles in 12 animals we suggest intervals of approximately 27 hours between the beginning of the LH peak and ovulation and of about 17 hours between the end of the peak and ovulation. Intervals between the beginning of heat and ovulation appear irregular and cannot be used with certainty as a reference point to predict ovulation. Five ovulations were observed closely and in the five cases, the formation of an apex was noted Our results clearly show that with the technique mentioned above we can predict rapidly and precisely bovine ovulation.

Animals↗
PubMed1983

Inhibition of ovulation in the rabbit by the antimitotic agent, colchicine.

This study establishes the optimum time to administer colchicine to inhibit ovulation in the rabbit, and it examines the effect of colchicine on prostaglandin biosynthesis in ovulatory follicles. Colchicine (2 mg/kg) was given at intervals ranging from 50 hours to 2 hours before ovulation. The ovulation efficiency was significantly reduced when colchicine was administered between 30 hours and 9 hours before ovulation, with maximum inhibition occurring at 20 hours before ovulation. Normal elevation in prostaglandin biosynthesis at the time of ovulation was significantly reduced when colchicine was given at 20 hours before ovulation, but not when it was given at 9 hours or 2 hours before ovulation. The results suggest that the mechanism by which the antimitotic agent colchicine inhibits prostaglandin biosynthesis and ovulation may be different from that of the nonsteroidal antiinflammatory agent indomethacin.

Animals↗
PubMed1982

Ovulation detection in the human.

The importance of predicting human ovulation for either optimizing or avoiding conception has been considered from an endocrine, morphological and clinical view point. Of the biochemical markers in peripheral blood, a knowledge of the LH peak is the most clearly defined, with a two to four fold increase above baseline levels for a relatively short 24-30 hour preovulatory period. Ovulation is considered to occur 28-36 hours after the beginning of the LH rise or 8-20 hours after the LH peak. Daily assessment of the rise in preovular oestrogen reflects Graafian follicle development but the rise is less distinct and spread over 3-4 days with marked day to day fluctuations. LH induces a marked reduction in oestrogen production some 12 hours prior to ovulation and at the same time induces a two to three fold increase in progesterone production above baseline levels. While these changes in themselves are not great enough for day to day discrimination, a knowledge of their reciprocal relationship may be. The preovular rise in FSH is relatively small compared to LH and the radioimmunoassay technique has not generally been refined to be as rapid and reliable. Monitoring the day to day growth of the preovular follicle ultrasonically is both linear and potentially predictable but there is a wide range of its final diameter (17-26 mm) prior to ovulation making prediction inaccurate. With further refinements in ultrasonic resolution, detection of intrafollicular changes of the cumulus oophorus and granulosal cell layer configuration and thickness may give a closer prediction of the time of ovulation. At a clinical level a knowledge of menstrual cycle length in association with body messages which herald ovulation are useful and may forewarn that ovulation in terms of days is approaching. Such markers as preovulation pain, the detection of periovular cervical mucus and the change in physical character and position of the cervix are reliable signs of preovulation for many well motivated and informed women for either promoting or avoiding conception. A knowledge of the basal body temperature is not a prospective guide to ovulation, but once the thermal shift is established in association with loss of periovular mucus symptoms, the fertile period can be considered to have passed. Because we do not have a precise and simple marker of human ovulation, it is necessary that the most suitable marker of pre- or postovulation is chosen for the particular need in a given individual.

Body Temperature↗