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1.
The effect of pretreatment with flurogestone acetate (FA) on the lifespan of corpora lutea induced with pregnant mare serum gonadotropin (PMS) was examined in cycling and anestrous ewes. Cycling ewes received one of three treatments: 750 IU PMS 2 d before expected estrus (P), FA-impregnated vaginal sponges for 16 d (F), and FA sponges for 16 d and 750 IU PMS 2 d before sponge removal (FP). A fourth group served as controls (C). When compared with d 12 means within treatment, plasma progesterone means were lower (P less than .05) on d 16 in control ewes, on d 15 in P and F ewes, and on d 14 in FP ewes. Only 44% of ewes receiving FA treatment alone exhibited estrus (P less than .05) compared with 100% of untreated ewes. The FP treatment increased ovulation rate compared with controls (P less than .01). The decrease in luteal lifespan observed in cycling ewes suggests a possibility of asynchrony between the uterus and embryo, which could result in failure of an embryo to prevent luteal regression, thus resulting in reduced fertility. None of the seasonally anestrous ewes that received PMS alone and only 55% of those treated with FA sponges for 8 d before PMS injection exhibited estrus. Ewes pretreated with FA exhibited higher plasma progesterone concentrations on d 10 through 16 after PMS injection. There were no differences in luteal lifespan as measured by peripheral plasma progesterone patterns. Although FA treatment did not alter luteal lifespan in anestrous ewes, the increased plasma progesterone concentrations observed with FA treatment suggest that progestogen pretreatment may be essential for optimal luteal function.  相似文献   

2.
A study was done to test whether ovulatory follicles destined to form subfunctional corpora lutea differed from normal ovulatory follicles in steroidogenic function. Twenty-five ewes were treated with prostaglandin F2 alpha on d 11 of the estrous cycle, then unilaterally ovariectomized before (n = 13) or after (n = 12) the surge of luteinizing hormone (LH) at the induced estrus to collect "control" follicles, which would have produced normal corpora lutea. In 15 ewes, the second ovary was removed 63 to 84 h later to collect "treated" follicles before (n = 7) or after (n = 8) the second expected surge of LH. Five ewes (control) were allowed to ovulate from the remaining ovary at first estrus and another five (treated) at the second estrus (3 to 4 d later). Treated ewes had lower serum progesterone than control ewes during the ensuing cycle (P less than .05). Treated follicles contained less estradiol in the theca (4.4 +/- .6 vs 10.0 +/- 2.5 ng; P less than .05), less androstenedione (.1 +/- .1 vs 1.0 +/- .2 ng) and estradiol (.5 +/- .1 vs 2.9 +/- 2.2 ng) in the granulosa (P less than .05) and less progesterone in the follicular fluid (.8 +/- .4 vs 3.3 +/- .8 ng; P less than .05) than control follicles, when removed before the surge of LH. Follicles removed after the surge of LH did not differ. In conclusion, ovulatory follicles with low steroidogenic function became corpora lutea that secreted lower-than-normal quantities of progesterone.  相似文献   

3.
The influence of varying doses of human chorionic gonadotropin (hCG) on the preovulatory luteinizing hormone (LH) surge, estradiol-17 beta (E2) and progesterone (P4) was studied in synchronized gilts. Altrenogest (AT) was fed (15 mg X head-1 X d-1) to 24 cyclic gilts for 14 d. Pregnant mares serum gonadotropin (PMSG; 750 IU) was given im on the last day of AT feeding. The gilts were then assigned to one of four groups (n = 6): saline (I), 500 IU hCG (II), 1,000 IU hCG (III) and 1,500 IU hCG (IV). Human chorionic gonadotropin or saline was injected im 72 h after PMSG. No differences in ovulation rate or time from last feeding of AT to occurrence of estrus were observed. All gilts in Groups I and II expressed a preovulatory LH surge compared with only four of six and three of six in Groups III and IV, respectively. All groups treated with hCG showed a rapid drop (P less than .01) in plasma levels of E2 11, 17, 23 h after hCG injection when compared with the control group (35 h). The hCG-treated gilts exhibited elevated P4 concentrations 12 h earlier than the control group (3.1 +/- .5, 3.4 +/- .72, 3.1 +/- .10 ng/ml in groups II, III and IV at 60 h post-hCG vs .9 +/- .08 ng/ml in group I; P less than .05). These studies demonstrate that injections of ovulatory doses of hCG (500 to 1,500 IU) had three distinct effects on events concomitant with occurrence of estrus in gilts: decreased secretion of E2 immediately after hCG administration, failure to observe a preovulatory LH surge in some treated animals and earlier production of P4 by newly developed corpora lutea.  相似文献   

4.
Experiments were conducted to examine the effects of exogenous GnRH and LH on serum concentrations of progesterone (P4) in the ewe. Ewes in Exp. 1 and 2 were laparotomized on d 2 of an estrous cycle and ewes with corpora lutea (CL) in both ovaries were unilaterally ovariectomized. Ewes with CL in one ovary only were not ovariectomized. While they were anesthetized, ewes (n = 5) were injected with 25 micrograms GnRH (Exp. 1) or 50 ng GnRH (Exp. 2) into the artery supplying the ovary bearing the CL. Control ewes (n = 5 in each experiment) were injected similarly with saline. In Exp. 3, six ewes were injected i.v. (jugular) on d 2 with 100 micrograms oLH (t = 0) and 50 micrograms oLH at 15, 30 and 45 min; six control ewes were injected similarly with saline. Jugular blood was collected from all ewes at frequent intervals after treatment for LH analysis and on alternate days of the cycle through d 10 or 11 for P4 analysis. Treatment with 25 micrograms GnRH increased serum concentrations of LH at 15, 30, 45 and 60 min postinjection (P less than .001) and reduced serum concentrations of P4 on d 7 through 11 (treatment x day interaction; P less than .05). Injection with 50 ng GnRH caused a slight increase in serum concentrations of LH at 15 min but had no effect on serum concentrations of P4.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
The hypothesis that subnormal luteal function after induced ovulation in anestrous ewes was the result of uterine influences exerted during the periovulatory period was tested. Crossbred ewes (n = 27) in seasonal anestrus were induced to ovulate by administration of 12 doses of 250 ng of LHRH at 2-h intervals, followed immediately by a bolus injection of LHRH (250 micrograms; d 0). Ewes were unilaterally hysterectomized on either d -3 (PRELHRH) or 2 (POSTLHRH). Daily blood samples were collected and assayed for progesterone (P4) and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM). All ewes were slaughtered on d 10, and corpora lutea (CL) were collected, weighed, and assayed for concentration of P4. All ewes that ovulated exclusively in the ovary ipsilateral to the remaining uterine horn had a transient increase in plasma P4 of 2 to 3 d (short luteal phase). In ewes with at least one CL in the isolated ovary, elevated plasma P4 was maintained after hysterectomy but was consistently lower (P less than .05) in POSTLHRH ewes than in PRELHRH ewes. Concentrations of PGFM did not differ between treatments. The CL ipsilateral to the remaining uterine horn weighted less (P less than .01) and contained less P4 (P less than .01) than contralateral CL. These data confirm the hypothesis that premature regression of subnormal CL is uterine-dependent in a local fashion. Presence of the uterus during the follicular and(or) early luteal phase inhibited subsequent luteal function in seasonally anestrous ewes.  相似文献   

6.
Two experiments were conducted during 2 yr to evaluate differences in ovulation potential and fertility in response to GnRH or hCG. In Exp. 1, 46 beef cows were given 100 microg of GnRH or 500, 1,000, 2,000, or 3,000 IU of hCG. Ovulation incidence was not different between GnRH and any of the hCG doses, indicating that ovulatory capacity of at least 500 IU of hCG was equivalent to GnRH. In Exp. 2, beef cows (n = 676) at 6 locations were assigned randomly to a 2 x 3 factorial arrangement of treatments. Main effects were: 1) pre-timed AI (TAI) treatment (GnRH or hCG) and 2) post-TAI treatment (saline, GnRH, or hCG) to initiate resynchronization of ovulation in previously inseminated cattle. Blood samples were collected (d -21 and -10) to determine progesterone concentrations and assess cyclicity. Cattle were treated with a progesterone insert on d -10 and with 100 microg of GnRH or 1,000 IU of hCG. A PGF(2alpha) injection was given at insert removal on d -3. Cows were inseminated 62 h (d 0) after insert removal. On d 26 after first TAI, cows of unknown pregnancy status were treated with saline, GnRH, or hCG to initiate a CO-Synch protocol. Pregnancy was diagnosed 33 d after first TAI to determine pregnancies per AI (P/AI). Nonpregnant cows at 6 locations in yr 1 and 1 location in yr 2 were given PGF(2alpha) and inseminated 56 h later, concurrent with a GnRH injection. Five weeks later, pregnancy diagnosis was conducted to determine pregnancy loss after first TAI and pregnancy outcome of the second TAI. Injection of pre-TAI hCG reduced (P < 0.001) P/AI compared with GnRH, with a greater reduction in cycling cows. Post-TAI treatments had no negative effect on P/AI resulting from the first TAI. Serum progesterone was greater (P = 0.06) 7 d after pre-TAI hCG than after GnRH and greater (P < 0.05) after post-TAI hCG on d 26 compared with saline 7 d after treatment in association with greater frequency of multiple corpora lutea. Compared with saline, injections of post-TAI GnRH and hCG did not increase second insemination P/AI, and inconsistent results were detected among locations. Use of hCG in lieu of GnRH is contraindicated in a CO-Synch + progesterone insert protocol. Compared with a breeding season having only 1 TAI and longer exposure to cleanup bulls, total breeding season pregnancy rate was reduced by one-third, subsequent calving distribution was altered, and 50% more AI-sired calves were obtained by applying 2 TAI during the breeding season.  相似文献   

7.
An experiment was conducted to evaluate the effect of exogenous gonadotropin releasing hormone (GnRH) on ovulation and embryonic survival in pubertal gilts. Gilts were assigned in replicates to a control (n = 10) and treatment (n = 10) group. Treatment consisted of an iv injection of 200 micrograms of GnRH immediately after initial mating on the first day of detected estrus. Control gilts were similarly injected with physiological saline. Blood samples were collected from the anterior vena cava immediately prior to injection, thereafter at 15-min intervals for 90 min, and subsequently, before slaughter on d 30 of gestation. Serum samples were analyzed for luteinizing hormone (LH) and progesterone by radioimmunoassay. Treatment with GnRH increased the quantity of LH released (P less than .05), with highest serum concentrations (ng/ml, means +/- SE) of gonadotropin in treated gilts (17.3 +/- 3.5) occurring at 75 min post-injection. In control gilts, serum concentrations of LH were not affected by injection of saline. Mean number of ovulations in treated gilts was also greater (P less than .05) than that of control animals (14.5 +/- .7 vs 12.1 +/- .6). However, treatment with GnRH did not enhance the number of attached conceptuses (normal and degenerating) present (treated, 10.9 +/- .9 vs control, 10.5 +/- .7) nor the percentage of viable fetuses (treated, 74.7 +/- 6.9 vs control, 83.5 +/- 5.0%) on d 30 of gestation. Although GnRH increased ovulation rate, mean weight of corpora lutea of treated and control gilts did not differ (402.8 +/- 16.3 vs 389.5 +/- 11.3 mg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
Two experiments were designed to examine whether hormonal profiles were related to luteal life span in pluriparous postpartum anestrous beef cows. Cows (Exp. 1, n = 34; Exp. 2, n = 23) received norgestomet (N) for 9 d or served as controls (C). Each cow received 1,000 IU human chorionic gonadotropin (hCG) 48 h after removal of N (d 0). Blood samples collected every 15 min for 8 h on d -5, 3 and 5 (Exp. 1) or on d -10 and -1 (Exp. 2) were assayed for luteinizing hormone (LH) and follicle stimulating hormone (FSH). Cortisol was determined in hourly samples collected on d -5 and in samples collected every 2 min during suckling on the same day (Exp. 1). Concentrations of 15-keto-13,14-dihydro-PGF2 alpha (PGFM) were determined in samples collected at 15-min intervals for 2 h on d -5, 3, 5 and 10 (Exp. 1). Estradiol-17 beta was measured in samples collected on d -5 (Exp. 1) or on d -10 and -1 (Exp. 2). Life span of induced corpora lutea was longer (P less than .05) in N than C cows. Percentages of N cows in which corpora lutea, formed in response to hCG, exhibited a normal life span were 83% on farm 1 and 25% on farm 2 (Exp. 1), and 90% (Exp. 2), compared with 0% in C cows. Concentrations of FSH were not affected by N but were lower (P less than .05) on d -5 in cows on farm 2 (.6 +/- .1 ng/ml) than in cows on farm 1 (.8 +/- .1 ng/ml). On d -5, a treatment X farm interaction (P less than .05) for mean LH was observed and frequency of pulses of LH was higher (P less than .01) in N than C cows (2.7 +/- .4 vs. .8 +/- .8 pulses/8 h). Neither cortisol nor PGFM was affected by N. Estradiol was increased in d -1 (6.1 +/- .5 vs 2.6 +/- .8 pg/ml; P less than .01) by N. It is suggested that pre-treatment with N enhanced life span of induced corpora lutea, in part, by influencing secretion of LH and development of follicles, but a threshold concentration of FSH was required for N to exert this effect.  相似文献   

9.
The incidence and cause of premature corpora lutea failure and the response to luteinizing hormone treatment was investigated in superovulated dairy goats. Does were treated with 1000 IU pregnant mare serum gonadotropin intramuscularly, followed by either luteinizing hormone (treated group) or saline (control group). Serum progesterone concentrations were used to monitor corpus luteum function. The dose of pregnant mare serum gonadotropin used induced superovulation in a majority of the does, but the responses varied depending on the time of year. Premature regression of the corpora lutea occurred in 4 of 18 does after pregnant mare serum gonadotropin treatment, but there was no difference in the incidence of corpora lutea failure between treated and control groups. Decreases in serum progesterone concentrations were evident by day 3 after ovulation in does that experienced corpora lutea failure indicating this to be the critical time for premature regression of the corpora lutea in superovulated does.  相似文献   

10.
This study was conducted to determine whether chronic hCG treatment would cause regression of induced corpora lutea (CL) in mature cyclic gilts. Thirty-two mature gilts that had displayed one or more estrous cycles of 18 to 22 d were used. Sixteen gilts were hysterectomized (HYSTX) on d 6 to 9 (d 0 = onset of estrus) and their CL were marked with charcoal (spontaneous group). Sixteen gilts (induced group) were injected with 1,500 IU of pregnant mare's serum gonadotropin (PMSG) on d 6 and 500 IU of hCG on d 9 (day of hCG = d 0 of the induced cycle). Ovulation was assumed to occur on d 2 of the induced cycle. Induced gilts were HYSTX on d 8 to 9 (d 17 to 18 of the original spontaneous cycle) and their CL were marked with charcoal. Only gilts (n = 14) in which induced CL were present and in which the original CL had regressed were then subjected to treatment with saline or hCG. From d 10 to 29, gilts with spontaneous CL were injected daily with 500 IU of hCG (n = 8) or saline (n = 8). From d 10 to 29 of the induced cycle, induced gilts were injected daily with 500 IU of hCG (n = 6) or saline (n = 8). Jugular blood samples were collected every other day from all gilts beginning on the 1st d of daily hCG treatment and quantified for estradiol and progesterone by RIA. On the day after the last hCG injection, the number of charcoal-marked CL and charcoal-marked corpora albicantia (CA) were determined.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

11.
Gilt oestrus and ovulation responses to injection of a combination of equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) (PG600) can be unpredictable, possibly reflecting inadequate circulating LH activity. The objective of this study was to determine the effect of PG600 followed by supplemental hCG on gilt ovarian responses. In experiment 1, 212 Hypor gilts (160 day of age) housed on two farms in Spain received intramuscular (i.m.) injections of PG600 (n = 47), or PG600 with an additional 200 IU hCG injected either concurrently (hCG‐0; n = 39), or at 24 h (hCG‐24; n = 41) or 48 h (hCG‐48; n = 45) after PG600. A further 40 gilts served as non‐injected controls. Ovulation responses were determined on the basis of initial blood progesterone concentrations being <1 ng/ml and achieving >5 ng / ml 10 d after the PG600 injection. The incidence of ovulating gilts having progesterone concentrations >30 ng/ml were recorded. During the study period, 10% of control gilts ovulated whereas 85–100% of hormone‐treated gilts ovulated. There were no significant differences among hormone groups for proportions of gilts ovulating. The proportions of gilts having circulating progesterone concentrations >30 ng/ml were increased (p ≤ 0.02) in all hCG treated groups compared with the PG600 group. In experiment 2, a total of 76 Hypor gilts at either 150 or 200 days of age were injected with PG600 (n = 18), 400 IU eCG followed by 200 IU hCG 24 h later (n = 20), PG600 followed by 100 IU hCG 24 h later (n = 17), or 400 IU eCG followed by 300 IU hCG 24 h later (n = 21). Blood samples were obtained 10 days later for progesterone assay. There were no effects of treatment or age on incidence of ovulation, but fewer 150‐day‐old gilts treated with PG600 or 400 IU eCG followed by 200 IU hCG had progesterone concentrations >30 ng / ml. We conclude that hCG treatment subsequent to PG600 treatment will generate a higher circulating progesterone concentration, although the effect is not evident in older, presumably peripubertal, gilts. The mechanism involved and implications for fertility remain to be determined.  相似文献   

12.
The ovulatory response of ewes from breeds that differ widely in prolificacy (Ile-de-France, ++ Booroola Merino, Romanov, F+ Booroola Merino and F+ Booroola Romanov with adult ovulation rates of about 1.5, 1.2, 3, 3 and 3.5 respectively) to 750 IU of hCG given at different physiological stages (before puberty, during anestrus or during the luteal phase) was compared. In all except one experiment, hCG induced ovulation in 73 to 98% of the lambs, indicating that follicles sensitive to LH were present at all stages studied. Ranking of the breeds according to hCG-induced ovulation rate in prepuberal lambs was similar to that based on adult ovulation rate. Furthermore, hCG induced more ovulations in prepuberal F+ than in ++ lambs (3.7 +/- 1.4 vs 1.7 +/- .8 at 4.5 mo of age) as well as in anestrous ewes (F + at 3.1 +/- 1.8 vs ++ at 1.6 +/- .7). Within ewes, the correlation between hCG-induced ovulation rate and mature ovulation rate was positive in nonprolific breeds but not significant in prolific breeds. We conclude that 1) the number of hCG-induced ovulations can be used to identify sheep that are carriers of the Booroola gene and 2) the mechanisms responsible for a number of large ovulatory follicles typical of a breed are present at stages (prepuberal, anestrus, luteal phase) other than the follicular phase.  相似文献   

13.
The effects of pregnancy and number of corpora lutea on luteal regression induced with prostaglandin F2 alpha (PGF2 alpha) were examined in 93 ewes. Bred and nonpregnant ewes were assigned randomly to receive a single im injection of PGF2 alpha: 0, 2, 4, 6, 8 or 10 mg/58 kg body weight. Injections were given on d 13 postestrus. The concentration of progesterone in serum 24 h after PGF2 alpha injection was affected by dose (P less than .001). The effect of pregnancy and the interaction of pregnancy with number of corpora lutea on levels of progesterone in serum were significant (P less than .05); therefore, data were partitioned according to pregnancy status and analyzed separately. There was an effect of number of corpora lutea on serum concentration of progesterone in pregnant (P less than .01) but not nonpregnant ewes (P greater than .10). Similar relationships among groups were observed for the concentration of progesterone in luteal tissue. In nonpregnant ewes the minimum dose of PGF2 alpha to produce a significant suppression of progesterone in serum (P less than .05) was 4 mg/58 kg body weight. In pregnant ewes with one or two corpora lutea, the minimum effective doses were 6 and 10 mg/58 kg body weight, respectively. The concentration of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) in serum was related to the dose of PGF2 alpha injected. There were no differences in the concentration of PGFM in serum between pregnant and nonpregnant ewes either before or after injection. Corpora lutea of early pregnancy appear to be resistant to the luteolytic effect of PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

14.
The purpose of this experiment was to determine the ovulation rate after treatment with human chorionic gonadotropin (hCG) in two groups of gilts characterized by different ovarian morphology: grape-type (GT; n = 11) and honeycomb-type (HT; n = 7). At 170 d of age (d 0), gilts were examined by laparoscopy and ovarian type was determined by the distribution of macroscopic follicles present on the ovarian surface. Five to ten minutes after surgery, each gilt received a single injection (i.m.) of 750 IU of hCG. At d 0, GT ovaries had a greater number of large follicles (greater than or equal to 6 mm) than HT ovaries (10.0 +/- .5 vs 2.6 +/- .3; P less than .05), whereas HT ovaries had more small follicles (1 to 3 mm; HT: 42.3 +/- .8 vs GT: 26.7 +/- .9; P less than .05) and total follicles (HT: 59.4 +/- 2.3 vs GT: 52.2 +/- 1.5; P less than .05), although numbers of medium follicles (4 to 5 mm) were similar (GT: 15.6 +/- .8 vs HT: 14.6 +/- 1.7; P greater than .10). Number of induced corpora lutea (CL) per ovary was greater (P less than .05) in gilts with GT ovaries (10.59 +/- 2.9 CL) than in gilts with HT ovaries (5.21 +/- .66 CL). Total weight of luteal tissue (LT) per ovary and serum progesterone concentrations 8 d after induction of ovulation were greater in GT gilts than in HT gilts (GT: 6.37 +/- 1.09 g vs HT: 3.31 +/- .49 g for LT, P less than .05; GT: 21.08 +/- 4.76 ng/ml vs HT: 13.40 +/- 2.05 ng/ml for progesterone, P less than .07).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

15.
With the objective of controlling the day of ovulation, 40 mares were assigned to a control or three treated groups: A3d, A4d, and A5d. The treated groups received antarelix (Teverelix 0.01 mg/kg, i.v., twice a day) for 3, 4, or 5 days from the day the dominant follicle (F1) reached 28 mm (=D0), and one injection of hCG (1600 IU, i.v.) on D1, D2, or D3, respectively. Control mares received one injection of hCG when F1 reached 35 mm. Plasma LH, FSH, progesterone, and total estrogens were assayed. In the A3d, A4d, and A5d groups, 9 (90%), 6 (60%), and 5 (50%) out of 10 mares, respectively, ovulated on the expected day (i.e. between 24 and 48 h after hCG injection). In the control group, 7/10 (70%) presented the typical response to hCG. For 3 mares in both the A4d and A5d groups, the dominant follicle at the time the treatment was started did not ovulate and ovulation was postponed for between 11 and 15 days after the end of treatment. In the treated mares, the LH surge was abolished, and total estrogens were depressed during the preovulatory peak but the concentrations of FSH were not modified. Endocrine parameters were not altered in postponed cycles. Fertility did not differ in treated and control cycles. These results demonstrate that in mares: (1) ovulation can be programmed on a specific day of a 3-day period, with a success rate of 67%, by a treatment associating antarelix and one injection of hCG; (2) nevertheless in 20% of cases the dominant follicle regresses and does not ovulate; (3) for these mares ovulation is postponed by approximately 2 weeks; (4) terminal growth of the preovulatory follicle only requires low circulating concentrations of LH but atresia induced by a GnRH antagonist is significant when this treatment is administrated for more than 18 h.  相似文献   

16.
To identify the time characteristics of ovulation, 5 bitches were evaluated during heat by ultrasonography, laparoscopy and hormonal assay. Blood collections for progesterone and oestradiol 17-β assys and ultrasonography were performed every day and laparoscopy every other day. At ultrasonography, ovaries appeared as anechoic structures about 5 days before the estimated LH peak and gradually increased in size. The greatest changes were observed between days 2 and 4 post-LH peak: echogenicity varied greatly from one animal to another and from one day to the following going from totally anechoic to mixed hypo and hyperechogenicity. Then from day 6, ovaries always appeared as hypoechoic structures assimilated to corpora lutea. At laproscopy, small follicies were seen as early as day 10 before the LH peak. Their size slowly increased to become large protubering follicies around the day of LH peak (day 0). At day 1, corpra luta were observed for the first time and were present in all animals by day 5. During that period preceeding day 5, some ovaries had both corpora lutea and follicies clearly visible on their surface. In one animal, haemorrhagic foci were observed at day 3. Neither ultrasonography, nor laparoscopy allowed precise determination of the time of ovulation. Indeed, follicle collapses was never observed, but changes in echogenicity and in the appearance of the ovaries observed by laparoscopy, suggested that ovulation occurred between days 2 and 4 when progestrone concentrations were 12.6 ± 6.2 and 32.1 ± 10.9 nmol/L, respectively.  相似文献   

17.
We studied the effects of gonadotrophins and prostaglandin (PG) F2α on ovulation in gilts. Twenty-eight gilts were induced to ovulate using 750 IU pregnant mares serum gonadotrophin (PMSG) and 500 IU human chorionic gonadotrophin (hCG), administered 72 h apart. At 34 and 36 h after hCG, gilts received injections of either 500 μg or 175 μg PGF2α (cloprostenol), or had no injections. Laparotomies were performed at 36 h (cloprostenol gilts) or 38 h (controls) after hCG injection. The ovaries were examined and the proportion of preovulatory follicles that had ovulated (ovulation percent) was determined at 30 min intervals for up to 6 h. The number of gilts in which ovulation was initiated and the ovulation percent increased (p<0.001) with time, but was not affected by treatment. Many medium sized follicles (≤6 mm) were also observed to ovulate, or to exhibit progressive luteinization without overt ovulation, during the surgical period. A discrepancy between numbers of preovulatory follicles and corpora lutea suggests that luteal counts may not be an accurate assessment of ovulation rate following gonadotrophic stimulation.  相似文献   

18.
In 3 adult female cheetahs, induced-superovulation treatment was conducted, by means of 200 IU of pregnant mare serum gonadotropin (PMSG) and 100 IU of human chorionic gonadotropin (hCG) 80 hr after PMSG. The administration of PMSG created a sharp increase in the estradiol-17beta concentration, resulting in 232 pg/ml 8 hr later in one specimen out of three. The hCG administration showed an increase in the progesterone concentration of 2.29 ng/ml 46 hr later. In addition, after direct observation of the ovary surface by laparoscopy, 5 follicles in the right ovary over 2 mm in diameter, and 7 corpora lutea (5 in the right ovary and 2 in the left) were found. It is assumed that ovulation can be induced with hCG after 80 hr on PMSG during a cheetah's diestrus or proestrus.  相似文献   

19.
Applicability of ovulation synchronization protocol using GnRH and PGF(2alpha) (PGF) injection to anestrous beef cows remains controversial. We compared the effectiveness of the protocol in the anestrous stage of the beef cow with that in the cycling stage using the same animals. Ovaries of five Japanese Black and three Japanese Shorthorn cows were ultrasonographically examined, and blood samples were collected daily for hormonal analyses. Each animal received the protocol twice (Day -6 to -8: GnRH, Day 0: PGF, Day 2: GnRH). Additional blood samples were taken before and after GnRH injection for LH and FSH measurements to evaluate the pituitary function. For the ovarian status at the onset of the protocol cows were divided into anestrous (n=8) and cycling (n=8) stages. There was no significant difference in size of the dominant follicle at the first and second GnRH injections, and in the magnitude of the pituitary response to GnRH between the two stages. However, the size of the corpus luteum and progesterone concentrations at the PGF injection in the anestrous stage were significantly smaller and lower (P<0.01), respectively, and ovulation synchronization rate in the anestrous stage was significantly lower (P<0.05) than in the cycling stage. In conclusion, ovulation synchronization protocol in anestrous beef cows has limited effectiveness.  相似文献   

20.
The aim of the current study was to determine the possible effects of progestagen oestrous synchronization on vascular endothelial growth factor (VEGF) expression during sheep luteogenesis and the peri‐implantation period and the relationship with luteal function. At days 9, 11, 13, 15, 17 and 21 of pregnancy, the ovaries from 30 progestagen treated and 30 ewes cycling after cloprostenol injection were evaluated by ultrasonography and, thereafter, collected and processed for immunohistochemical evaluation of VEGF; blood samples were drawn for evaluating plasma progesterone. The progestagen‐treated group showed smaller corpora lutea than cloprostenol‐treated and lower progesterone secretion. The expression of VEGF in the luteal cells increased with time in the cloprostenol group, but not in the progestagen‐treated group, which even showed a decrease between days 11 and 13. In progestagen‐treated sheep, VEGF expression in granulosa‐derived parenchymal lobule capillaries was correlated with the size of the luteal tissue, larger corpora lutea had higher expression, and tended to have a higher progesterone secretion. In conclusion, the current study indicates the existence of deleterious effects from exogenous progestagen treatments on progesterone secretion from induced corpora lutea, which correlate with alterations in the expression of VEGF in the luteal tissue and, this, presumably in the processes of neoangiogenesis and luteogenesis.  相似文献   

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