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PubMed2005

Influence of time of insemination relative to ovulation and frequency of insemination on gilt fertility.

The objectives of this study were to determine the optimal time of insemination in the pre-ovulatory period (from 32 to 0 h before ovulation) and to evaluate once-daily versus twice-daily inseminations in gilts. In Experiment 1, pre-puberal gilts (n=102) were observed for estrus every 8h and ultrasonography was performed every 8h from the onset of estrus to confirmation of ovulation. The gilts were inseminated once with 4 x 10(9) spermatozoa at various intervals prior to ovulation. Pregnancy detection was conducted 24 days after AI and gilts were slaughtered 4-6 days later. Corpora lutea and the number of viable embryos were counted and the embryo recovery rate was calculated (based on the percentage of corpora lutea). Inseminations performed <24h before ovulation resulted in a higher embryo recovery rate (P=0.02) and produced 2.1 more embryos (P=0.01) than inseminations >or=24h before ovulation. However, the pregnancy rate was reduced when inseminations were performed >16 h before ovulation (P=0.08). In Experiment 2, pre-puberal gilts (n=105) were observed for estrus every 12h and ultrasonography was performed every 12h from the onset of estrus to confirmation of ovulation. Gilts were inseminated (with 4 x 10(9) spermatozoa) 12h after the onset of estrus, with inseminations repeated either every 12h (twice-daily) or 24h (once-daily) during estrus. The gilts were allowed to farrow. There were no differences (between gilts bred twice-daily versus once-daily) for return to estrus rate (P=0.36) and adjusted farrowing rate (P=0.19). However, gilts inseminated once-daily had 1.2 piglets less than those inseminated twice-daily (P=0.09). In conclusion, gilts should be inseminated up to 16 h before ovulation, as intervals >16 h reduced pregnancy rate and litter size.

Animals↗
PubMed1999

Lunelle monthly contraceptive injection (medroxyprogesterone acetate and estradiol cypionate injectable suspension): assessment of return of ovulation after three monthly injections in surgically sterile women.

The pharmacodynamic effects of medroxyprogesterone acetate (MPA) and estradiol cypionate (E2C) (MPA/E2C) (Lunelle Monthly Contraceptive Injection) on ovarian function were assessed through changes in serum progesterone concentrations. The data described here were obtained simultaneously with pharmacokinetic data presented in another article in this issue. Sixteen surgically sterile women with regular menstrual cycles were studied for one control cycle, three consecutive treatment months, and 3-5 months of follow-up. Suppression, followed by resumption of ovulation (the dynamic end point), was assessed by serum progesterone levels. Return of ovulation was presumptive based on progesterone concentrations > or = 4.7 ng/mL, as ultrasound was not used to determine the follicular/ovulatory status of these subjects. Luteal-like serum progesterone peaks were observed in all 16 women before drug administration, confirming the presence of ovulatory cycles. After the third monthly injection of MPA/E2C, progesterone concentrations were measured until demonstration of ovulation. Two women discontinued and three were lost to follow-up before this objective was achieved. Serum progesterone levels and, consequently, ovulation were suppressed beyond the entire dosing interval, indicated by the absence of any luteal-like progesterone peaks (serum progesterone concentrations did not exceed 1 ng/mL). The first normal ovulatory cycle, based on progesterone concentrations > or = 4.7 ng/mL, was observed in 11 women between days 63 and 112 after the third injection. Select medroxyprogesterone acetate parameters (i.e., area under the curve and minimum concentration) were correlated with return of ovulation. The correlation coefficients (r) were 0.757 and 0.492 for area under the curve and minimum concentration, respectively, indicating that return of ovulation is dependent, in part, on area under the curve and on the magnitude of the serum MPA trough level. In general, the higher the minimum concentration levels, the longer the time to return of ovulation. In conclusion, the return of ovulation, as confirmed by serum progesterone concentrations > or = 4.7 ng/mL, was observed as early as 63 days after the third and final monthly intramuscular injection of MPA/E2C, suggesting that consistent suppression of the hypothalamic-pituitary-ovarian axis is reversible after discontinuation of dosing.

Contraceptive Agents, Female↗
PubMed1991

Follicular size at the time of human chorionic gonadotropin administration predicts ovulation outcome in human menopausal gonadotropin-stimulated cycles.

OBJECTIVE: The objectives of this study were: (1) to correlate follicle size by transvaginal sonography with ovulation outcome in cycles of controlled ovarian hyperstimulation with human menopausal gonadotropins; (2) to determine if follicular size on the day of human chorionic gonadotropin (hCG) administration predicts the incidence of ovulation; and, if so, (3) to derive a mathematical model that predicts the number of expected ovulations in any given cycle of controlled ovarian hyperstimulation. DESIGN: A retrospective analysis. PARTICIPANTS: Forty-nine consecutive patients undergoing 122 cycles of controlled ovarian hyperstimulation were studied in a tertiary care setting. MAIN OUTCOME MEASURES: Follicular size and evidence of ovulation were determined sonographically. The main outcome measure was the rate of ovulation per follicle size. RESULTS: The percentages of follicles measuring less than or equal to 14 mm, 15 to 16 mm, 17 to 18 mm, 19 to 20 mm, and greater than 20 mm on the day of hCG administration that subsequently ovulated were 0.5%, 37.4%, 72.5%, 81.2%, and 95.5%, respectively. CONCLUSIONS: (1) Follicular size on the day of hCG administration correlates with the incidence of ovulation. (2) The expected number of ovulations in any given controlled ovarian hyperstimulation cycle can be predicted with 95% confidence using the accompanying equation.

Chorionic Gonadotropin↗
PubMed2001

Reliability of ovulation tests in infertile women.

OBJECTIVE: To assess the reliability of the most widely used clinical methods for predicting or confirming ovulation. METHODS: We monitored spontaneous cycles in 101 infertile women using basal body temperature (BBT), transvaginal ultrasound, a urinary stick system for LH surge, and three serum progesterone measurements in the midluteal phase. Transvaginal ultrasound monitoring was standard for ovulation detection and sensitivity. We calculated specificity and accuracy of each method compared with that standard. RESULTS: Follicular development and ultrasound evidence of ovulation were confirmed in 97 of 101 cycles (96%). Urinary LH surge preceded follicular rupture assessed by ultrasonography in all cycles and showed concordance with ultrasound-evidenced ovulation in 98 of 101 cases. The timing of BBT nadir had wide variability, and BBT and ultrasonography agreed in a similar percentage of cases (74%). Midluteal serum progesterone assessments showed ovulatory values in 93 subjects, and ovulation was concordant with ultrasonography in 90 subjects. CONCLUSION: Urinary LH was accurate in predicting ovulation with ultrasonography as the standard for detection, but time varied widely. The nadir of BBT predicted ovulation poorly. The BBT chart was less accurate for confirming ovulation, whereas a single serum progesterone assessment in midluteal phase seemed as effective as repeated serum progesterone measures.

Adolescent↗
PubMed2000

Timing of insemination relative to ovulation in pigs: effects on sex ratio of offspring.

The objective of the present study was to identify effects of the interval between insemination and ovulation in pigs on the sex ratio and sex ratio dispersion of offspring. Crossbred sows that had farrowed 2 to 9 litters were weaned (Day 0) and came into estrus between Days 3 and 7 after weaning. Ultrasonography was performed every 6 h, from 12 h after the onset of estrus until ovulation had been observed. The sows were inseminated once at various intervals from the onset of estrus. At farrowing, the numbers of viable piglets and dead piglets were recorded per sow. In four 12-h intervals between insemination and ovulation (36 to 24 h before ovulation, 24 to 12 h before ovulation, 12 to 0 h before ovulation and 0 to 12 h after ovulation), the total number of piglets was (mean+/-SEM) 10.8+/-1.2 (n=15); 13.4+/-0.7 (n=23); 13.2+/-0.9 (n=21); and 12.1+/-1.0 (n=16), respectively (P>0.05). The percentage of male piglets per litter in the four 12-h intervals was 52.1+/-3.6, 50.5+/-2.7, 54.9+/-2.8 and 47.8+/-4.5, respectively (P>0.05). Sex ratio was not influenced by litter size (P>0.05), and its distribution was normally dispersed (i.e., as expected under a binomial distribution) in all 4 intervals between insemination and ovulation (P>0.05).

Animals↗
PubMed2001

Use of buserelin to induce ovulation in the cyclic mare.

Inducing ovulation in a cyclic mare is often necessary. For this purpose, hCG has been used commonly, but the response can be reduced after successive administrations. The aims of this study were to test the effectiveness of buserelin in hastening ovulation in estrus mares, and its influence on fertility; and to investigate the effect of treatment on LH secretion. Five crossover trials were designed to compare the effect of two treatments: buserelin (40 microg in 4 doses i.v. at 12 h intervals) vs placebo (Experiments 1 and 2); buserelin 40 microg (in 4 doses i.v.) vs 20 microg (Experiment 3); buserelin (4 doses of 20 microg i.v.) vs hCG (1 dose of 2,500 IU i.v.) (Experiment 4); or buserelin (3 doses of 13.3 microg at 6 h interval) vs hCG (Experiment 5). In Experiment 2, blood samples were taken hourly until ovulation, for LH measurements. In Experiment 1, buserelin treatment significantly hastened ovulation. Reduction of the dose by half (Experiment 3) did not alter the effectiveness. In Experiments 4 and 5, buserelin was as effective as hCG in inducing ovulation between 24 and 48 h after initiation of treatment. Buserelin treatment induced a rise in LH concentration during the 48 h period of the experiment, and LH concentrations before ovulation were significantly higher in buserelin treated cycles than in placebo cycles. These experiments demonstrated the usefulness of two new protocols of administration of buserelin, as an alternative to hCG for induction of ovulation. One hypothesis explaining the mechanism of action is that the persistant rise in LH concentration could modify the ratio of biological/immunological LH, as it occurs physiologically, thereby hastening ovulation.

Animals↗
PubMed2003

Effect of time of ovulation and sperm concentration on fertilization rate in gilts.

In normal production practices, sows and gilts are inseminated at least twice during estrus because the timing of ovulation is variable relative to the onset of estrus. The objective of this study was to determine if a normal fertilization rate could be achieved with a single insemination of low sperm number given at a precise interval relative to ovulation. Gilts (n=59) were randomly assigned to one of three treatment groups: low dose (LD; one insemination, 0.5 x 10(9) spermatozoa), high dose (HD; one insemination, 3 x 10(9) spermatozoa) or multiple dose (MD; two inseminations, 3 x 10(9) spermatozoa per insemination). Twice daily estrus detection (06:00 and 18:00 h) was performed using fenceline boar contact and backpressure testing. Transrectal ultrasonography was performed every 6 h beginning at the detection of the onset of standing estrus and continuing until ovulation. Gilts in the LD and HD groups were inseminated 22 h after detection of estrus; MD gilts received inseminations at 10 and 22 h after detection of estrus. Inseminations were administered by using an insemination catheter and semen was deposited into the cervix. The uterus was flushed on Day 5 after the onset of estrus and the number of corpora lutea, oocytes, and embryos were counted. Time of insemination relative to ovulation was designated as 40 to >24 h, 24 to >12 h, and 12 to 0 h before ovulation and >0 h after ovulation. The LD gilts had fewer embryos (P<0.04), more unfertilized oocytes (P<0.05) and a lower fertilization rate (P<0.07) compared to MD gilts. The effects of time of insemination relative to ovulation and the treatment by time interaction were not significant. We conclude that a cervical insemination with low spermatozoa concentration may not result in acceptable fertility even when precisely timed relative to ovulation.

Animals↗
PubMed2003

Use of a GnRH antagonist, antarelix, associated or not with hCG, to control ovulation in cyclic pony mares.

The GnRH antagonist antarelix (Teverelix) was administered to mares (0.01 mg/kg, i.v., twice a day) during the periovulatory period. In Experiment 1, 20 mares were divided into a treated (A3d-) and a control (Control-) group. A3d- mares received antarelix for 3 days from the day when the dominant follicle (F1) reached 32 mm (D0). In Experiment 2, 10 mares were divided into a treated (A6d+) and a control (Control+) group. A6d+ mares received antarelix for 6 days from D0 and hCG was injected in all animals (1600 IU, i.v.) on D1. Pregnancies were determined 13 days after ovulation. In both experiments, antarelix interrupted or totally abolished the LH surge. In Experiment 1, 5/10 of the A3d- mares (with maximum LH concentrations of 11.6 ng/ml at the beginning of treatment) ovulated at the same time as the Control- mares; the other five mares (with LH concentrations under 5.4 ng/ml) ovulated 13.4+/-0.6 days later. In Experiment 2, all the A6d+ mares ovulated at the same time as the Control+ mares. In treated mares which ovulated during the treatment, progesterone concentrations and fertility did not differ from control mares. These results demonstrate that in mares: (1) a small elevation of endogenous LH can induce ovulation, (2) ovulation can be postponed approximately 13 days after a 3-day antarelix treatment if initiated just before the preovulatory LH surge, (3) ovulation can be induced by hCG on depressed levels of endogenous LH, (4) the inhibition of the post ovulatory LH surge has no effect either on the corpus luteum or on fertility.

Animals↗
PubMed2001

Ovulation in the tree shrew (Tupaia belangeri) induced by gonadotrophins.

The induction of ovulation by exogenous gonadotrophins is an important approach for recovering oocytes used for studies on the reproductive biology of some mammals. In the present study, pregnant mare serum gonadotrophin (PMSG) and human chorionic gonadotrophin (hCG) were used to induce ovulation in the tree shrew (Tupaia belangeri) using the following regimens. Groups A1-A3, multiple injections of PMSG (30-60 IU) followed by a single dose of hCG (30-60 IU); B1, combination of a single injection of PMSG (60 IU) with a single dose of hCG (60 IU); E1, combination of a single injection of PMSG (60 IU) with a single dose of hCG (30 IU) plus PMSG (30 IU); and administration of either PMSG (C1 and C2) or hCG (D1). The ovulation rate of animals producing oocytes with either first polar body or distinct perivitelline space, and the mean number of oocytes per animal were considered the most important criteria in each regimen. The most effective induction of ovulation was achieved in groups B1 and E1, with ovulation rates of 4/4 and 4/4, respectively, and mean numbers of ovulated oocytes per animal of 3.25 +/- 0.48 and 4.00 +/- 0.71 respectively. No ovulation was observed in the control group or in group D1. Therefore, regimes B1 and E1 were considered as the simplest and most effective for the induction of ovulation in the tree shrew.

Animals↗
PubMed2002

Development of a porcine follicle-stimulating hormone and porcine luteinizing hormone induced ovulation protocol in the seasonally anoestrus brushtail possum (Trichosurus vulpecula).

Monovulatory brushtail possums (Trichosurus vulpecula) were stimulated with exogenous hormones during seasonal anoestrus to overcome ovarian insensitivity and induce ovulation. Seasonal ovarian insensitivity to pregnant mare serum gonadotrophin (PMSG) was overcome by a new porcine follicle-stimulating hormone/porcine luteinizing hormone (pFSH/pLH) protocol. This protocol was refined because the original treatment produced oocytes with abnormal morphology. Possums (n = 12 per group) received eight injections of pFSH of 1.5, 3.0 or 6.0 mg per injection (at 12-h intervals for 4 consecutive days). Ovulation was induced 12 h after the final pFSH injection with a 4-mg injection of pLH. Control animals were treated with the established protocol of a single injection of 15 IU of PMSG, followed 48 h later with an injection of 4 mg of pLH. All females responded to pFSH/pLH treatment, although optimal stimulation occurred in those receiving 8 x 3 mg pFSH, with 13-14 ovulations and recovery of 11-12 oocytes per female (8 x 1.5 mg pFSH: 13 ovulations, 8-9 oocytes; 8 x 6 mg pFSH: 7-8 ovulations, 4-5 oocytes). In contrast, only seven of 12 females responded to PMSG/pLH and, of those responding, only 2-3 ovulations occurred and only 1-2 oocytes per female were recovered. However, around 80% of oocytes recovered after PMSG/pLH treatment had undergone nuclear maturation (metaphase II/1st polar body) compared with around 60% of oocytes from pFSH/pLH-treated animals. In possums killed from 27 to 39 h after pLH treatment, ovulation onset was first observed from 30 h and by 31.5 h, all animals had completed ovulation. Laparoscopic artificial insemination (LAI) was performed on pFSH/pLH-treated animals to determine whether the oocytes produced were capable of fertilization. Uterine LAI performed 27.5-28.5 h after pLH treatment yielded 11/26 fertilized oocytes (up to 4-cell stage), whereas vaginal LAI performed 13-14 h after pLH treatment yielded 21/53 fertilized oocytes. A proportion of oocytes generated from the refined pFSH/pLH protocol are thus properly mature and capable of fertilization. Further refinement of the protocol is now needed to improve the yield of fully matured oocytes.

Anestrus↗
PubMed1992

Gonadotrophin-induced oestrus and ovulation in the polyovulatory marsupial Sminthopsis crassicaudata.

Sminthopsis crassicaudata is a small (approximately 16 g) polyovulatory dasyurid marsupial which has the potential to become an important model species. This study examined the use of exogenous hormone treatment to manipulate the breeding of S. crassicaudata and as a means to obtain timed developmental stages for further study. Two thirds (21/32) of the females treated with 1.0 or 5.0 I.U. of pregnant mare serum gonadotrophin (PMSG) had ovulated when the contents of their reproductive tracts were examined 5 or 6 days later. Only one of eight females treated with 0.2 I.U. PMSG had ovulated in the same period. Although a similar proportion of animals treated with 1.0 I.U. and 5.0 I.U. ovulated, the ovulation rate was significantly lower when the higher dose was administered (mean of 10.5 ovulations per female v. 3.8 ovulations per female). In addition, the ovaries of 6/8 of the animals treated with 5.0 I.U. PMSG had luteinized follicles with degenerating oocytes, evidence of over-stimulation. Follicular luteinization also occurred in 4/8 animals treated with 1 I.U. PMSG. Oocyte maturation and ovulation occurred following PMSG stimulation without injection of synthetic gonadotrophin releasing hormone (GnRH). Treatment with a 10-micrograms dose of GnRH following PMSG seemed to have no effect on the outcome. Of the females that had ovulated by Day 6, three quarters had mated and some had fertilized eggs and two-cell embryos in the oviducts and uteri. In a further series of experiments the subsequent development of embryos conceived after PMSG treatment was assessed. Two thirds of treated females mated within 7 days of treatment and 60% of these matings yielded embryos when examined 11 days after PMSG. However, full-term development was only achieved in one animal. Gonadotrophin treatment of S. crassicaudata thus may have application as a means to obtain mature or maturing oocytes, cleavage stage embryos and blastocysts, but at this stage it appears not to offer promise as a method to achieve full-term development.

Animal Husbandry↗
PubMed1994

Male-induced oestrus and ovulation in female brush-tailed bettongs (Bettongia penicillata) suckling a young in the pouch.

Female brush-tailed bettongs isolated from males usually do not come into oestrus or ovulate. Individuals isolated during pregnancy and at parturition do not ovulate post partum and are in the unusual condition for a macropodoid of suckling a pouch young but lacking a quiescent corpus luteum or a diapause embryo. Females in this condition were tested for their ability to come into oestrus and to ovulate after re-introduction to the male. When returned to the male on Day 1 of lactation, females generally mated before Day 2 and ovulated; at all later stages of lactation, six or seven days after being returned to the male > or = 50% of females came into oestrus, mated and ovulated. The vaginal smears of most females in isolation were typical of post oestrus on Day 2; after being returned to the male on Day 11, these females came into oestrus in seven days, mated and ovulated. The results show that suckling a young in the pouch does not suppress ovulation in this species provided that an adult male is present. Moreover, the results indicate that the mechanism of male-induced ovulation 24 h post partum differs from that of the remainder of the pouch suckling period.

Animals↗
PubMed1996

Midcycle administration of a progesterone synthesis inhibitor prevents ovulation in primates.

Progesterone receptors appear in granuloma cells of preovulatory follicles after the midcycle gonadotropin surge, suggesting important local actions of progesterone during ovulation in primates. Steroid reduction and replacement during the gonadotropin surge in macaques was used to evaluate the role of progesterone in the ovulatory process. Animals received gonadotropins to induce development of multiple preovulatory follicles, followed by human chorionic gonadotropin (hCG) administration (day 0) to promote oocyte (nuclear) maturation, ovulation, and follicular luteinization. On days 0-2, animals received no further treatment; a steroid synthesis inhibitor, trilostane (TRL); TRL + R5020; or TRL + dihydrotestosterone propionate (DHT). On day 3, ovulation was confirmed by counting ovulation sites and collecting oviductal oocytes. The meiotic status of oviductal and remaining follicular oocytes was evaluated. Peak serum estradiol levels, the total number of large follicles, and baseline serum progesterone levels at the time of hCG administration were similar in all animals. Ovulation sites and oviductal oocytes were routinely observed in controls. Ovulation was abolished in TRL. Progestin, but not androgen, replacement restored ovulation. Relative to controls, progesterone production was impaired for the first 6 days post-hCG in TRL, TRL + R5020, and TRL + DHT. Thereafter, progesterone remained low in TRL but recovered to control levels with progestin and androgen replacement. Similar percentages of mature (metaphase II) oocytes were collected among groups. Thus, steroid reduction during the gonadotropin surge inhibited ovulation and luteinization, but not reinitiation of oocyte meiotic maturation, in the primate follicle. The data are consistent with a local receptor-mediated role for progesterone in the ovulatory process.

3-Hydroxysteroid Dehydrogenases↗
PubMed1978

Cell-to-cell communication and ovulation. A study of the cumulus-oocyte complex.

Cell-to-cell communication was characterized in cumulus-oocyte complexes from rat ovarian follicles before and after ovulation. Numerous, small gap junctional contacts were present between cumulus cells and oocytes before ovulation. The gap junction are formed on the oocyte surface by cumulus cell processes that transverse the zona pellucida and contact the oolemma. The entire cumulus mass was also connected by gap junctions via cumulus-cumulus interactions. In the hours preceding ovulation, the frequency of gap junctional contacts between cumulus cells and the oocyte was reduced, and the cumulus was disorganized. Electrophysiological measurements indicated that bidirectional ionic coupling was present between the cumulus and oocyte before ovulation. In addition, iontophoretically injected fluorescein dye was tranferred between the oocyte and cumulus cells. Examination of the extent of ionic coupling in cumulus-oocyte specimens before and after ovulation revealed that ionic coupling between the cumulus and oocyte progressively decreased as the time of ovulation approached. In postovulatory specimens, no coupling was detected. Although some proteolytic mechanism may be involved in the disintegration of the cumulus-oocyte complex, neither the cumulus cells nor the oocyte produced detectable levels of plasminogen activator, a protease which is synthesized by membrana granulosa cells. In summary, cell communication is a characterisitc feature of the cumulus-oocyte complex, and this communication is terminated near the time of ovulation. This temporal pattern of the termination of communication between the cumulus and the oocyte may indicate that communication provides a mechanism for regulating the maturation of the oocyte during follicular development before ovulation.

Animals↗
PubMed2006

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

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

Animals↗
PubMed1993

Endocrine composition of follicular fluid comparing human chorionic gonadotrophin to a gonadotrophin-releasing hormone agonist for ovulation induction.

Concentrations of inhibin, oestradiol and progesterone were determined in pre-ovulatory follicular fluid from 16 women undergoing in-vitro fertilization and embryo transfer treatment. A prospective randomized design was used such that ovulation was induced in eight women with human chorionic gonadotrophin (HCG) (9000 IU), and in eight women with an endogenous surge of luteinizing hormone (LH) and follicle stimulating hormone (FSH) caused by a single injection of gonadotrophin-releasing hormone agonist (GnRHa). Inhibin was measured by an enzyme-linked immunosorbent assay, and oestradiol and progesterone were measured by radio-immunoassay. Concentrations of inhibin and progesterone are significantly higher in follicular fluids collected after ovulation induction with HCG compared with ovulation induction with GnRHa (P < 0.001, P < 0.02, respectively). Concentrations of oestradiol were similar in the two groups. This study shows that the method by which ovulation is triggered significantly affects the micro-environment of the oocyte just prior to ovulation. The results indicate that HCG causes a prolonged luteotrophic effect well before ovulation, compared to an endogenous surge of gonadotrophins caused by GnRHa, and suggest that follicular maturation with an endogenous surge of gonadotrophins may be closer to the natural cycle than those cycles in which HCG is administered for ovulation induction. In addition, this study shows that the concentrations of inhibin and progesterone in follicular fluid may be valuable parameters in assessing the midcycle LH surge requirements for induction of ovulation.

Adult↗
PubMed1985

Effect of various agents on ovarian plasminogen activator activity during ovulation in pregnant mare's serum gonadotropin-primed immature rats.

The plasminogen activator/plasmin synthetic substrate S-2251 was used to measure the effect of indomethacin, cycloheximide, colchicine, dexamethasone, tranexamic acid, and aprotinin on the elevation of ovarian plasminogen activator (PA) that normally occurs during ovulation in the rat. Young Wistar rats were weaned on the morning of Day 21, given 4.0 IU of pregnant mare's serum gonadotropin (PMSG) s.c. at 0800 h on Day 22, and given 10.0 IU of human chorionic gonadotropin (hCG) on Day 24. These animals normally began ovulating between 0000 and 0200 h on Day 25. The induced ovulation rate was 11.5 +/- 2.2 ova/rat, based on the number of ova in the oviducts of control animals at 0900 h on Day 25. In the controls, PA activity in extracts of homogenized ovaries increased 3-fold from 0.125 +/- 0.010 OD units just before the administration of hCG to 0.371 +/- 0.021 at 12 h after hCG, i.e., near the time of ovulation. Indomethacin, in doses of 0.1-1.0 mg/rat, inhibited ovulation but did not inhibit the normal increase in PA activity, whereas indomethacin at the high dose of 10.0 mg/rat inhibited both ovulation and PA activity. Cycloheximide, at a dose of 0.1 mg/rat, was given at 12 h before hCG, immediately after hCG, and at 9 h after hCG. This agent inhibited ovulation most effectively when given at 12 h before hCG, yet it inhibited PA activity most effectively when given immediately after or at 9 h after hCG. Colchicine, at a dose of 0.1 mg/rat, inhibited ovulation, but not PA activity, when it was given 1 h before hCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The influence of prostaglandin E2 and indomethacin on progesterone production and ovulation in the rabbit ovary perfused in vitro.

The effects of prostaglandin E2 (PGE2) on the ovulation process were studied in a recirculating perfusion model using ovaries from virgin rabbits. Ovulation frequency, time of ovulation, and progesterone release from the ovaries were examined after the addition of PGE2, either alone or with luteinizing hormone (LH) in the presence or absence of indomethacin. The stimulatory effect of LH on ovulation was totally blocked if the ovaries were exposed to indomethacin at the same time. Ovaries treated with PGE2 alone did not ovulate, and PGE2 was unable to restore indomethacin-blocked ovulation. Conversely, the frequency of ovulation was reduced in ovaries treated with PGE2 and LH compared with controls receiving only LH. There was no measurable difference in the pattern of progesterone release between ovaries simultaneously treated with LH and indomethacin and LH-treated controls. Ovaries exposed to PGE2 alone showed only a slight increase of progesterone release in the medium, while those treated with PGE2 in combination with LH in the perfusate showed a smaller progesterone release than those treated with LH alone. The results confirm the blocking effect on ovulation by indomethacin. PGE2 could not reverse this effect, but instead reduced the number of LH-induced follicular ruptures. Indomethacin had no effect on progesterone levels, while PGE2 (which alone showed a slight stimulating effect on the steroid concentration) together with LH counteracted the effect of LH on progesterone release.

Animals↗