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1.
To investigate the factors contributing to the different ovulation rates observed in two strains of sheep (Booroola 5.2, Merino, 1.2) and after immunization against androstenedione (Immunized 1.8, Control 1.3), in vivo monitoring of follicular kinetics followed by histological examination of the ovaries was performed during the late luteal and follicular phases. Ewes had the three largest follicles of each ovary ink-labelled at days 13 and 15 and were ovariectomized after the beginning of oestrus.High ovulation rate was not associated with a more numerous antral follicle population in either Booroola ewes or immunized ewes. Furthermore, in Booroola ewes (r = 0.22) and in immunized ewes (r = ?0.02), there was no correlation between the number of antral follicles per ovary and the ovulation rate.The reasons for the high ovulation rate became clear when preovulatory enlargement was followed by ink-labelling. An extended period of time during which recruitment of ovulatory follicles takes place, together with a low incidence of selection through atresia and the ability of fully grown follicles to wait for ovulation are the features involved in the high ovulation rate of the Booroola ewes. A lower incidence of selection together with an unaltered recruitment leads to the increased ovulation rate noticed after immunization.  相似文献   

2.
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   

3.
The effects of different estrus synchronization techniques on follicular development and estrus response were studied in 81 nulliparous Boer does. The does were divided into nine groups. Eight of the nine groups were synchronized with prostaglandin F2-alpha (PGF(2α)) or flugestone acetate (FGA) or their combinations, and the ninth group was a control group. In addition to the above combinations, four of the eight synchronized groups were given 5?mg follicle-stimulating hormone (FSH) and the remaining four groups were administered 300?IU equine chorionic gonadotrophin (eCG). Posttreatment follicular development was monitored until ovulation occurred using a real-time B-mode ultrasound scanner (Aloka, 500 SSD, Japan), with a 7.5-MHz transrectal linear probe. All the does from the synchronized groups that were given eCG exhibited oestrus while only 88.9% of the does synchronized with FSH showed estrus. The estrus response was observed to be the least among the does synchronized with PGF(2α) + FSH (33.3%) combination followed closely by the FGA + FSH (42.9%) combinations. It was observed that the combinations of FGA + PGF(2α) + FSH resulted in increased percentage of estrus response, duration of estrus, and ovulation. The number of follicles was higher (P?相似文献   

4.
The aim of this study was to assess the ultrasonographic characteristics of ovulatory follicles in cyclic Western White Face ewes (December) that had received intravaginal sponges containing medroxyprogesterone acetate (MAP; 60 mg) for 12 days, with or without an injection of 500 IU of equine chorionic gonadotropin (eCG) at sponge removal. We hypothesized that quantitative echotextural attributes of the follicles in ewes treated only with MAP would differ from those in MAP/eCG-treated ewes, reflecting the increased antral follicular growth and secretory function under eCG influence. Digital images of ovulatory follicles obtained at 0 and 24 h after MAP sponge removal and at 24 h before ovulation in the eCG-treated (five ewes, 13 follicles) and control (six ewes, 9 follicles) animals, were subjected to computerized analyses. The mean diameter of ovulatory follicles increased (p < 0.001) 24 h after eCG treatment. The mean pixel intensity and heterogeneity of the follicular antrum (p < 0.001), as well as mean pixel intensity of the follicular wall and perifollicular ovarian stroma (p < 0.05), were greater in eCG-treated animals compared with control ewes 24 h after sponge removal and at 24 h before ovulation. Mean serum concentrations of oestradiol-17beta tended to increase (p = 0.06) 24 h after eCG treatment and the eCG-treated ewes exceeded (p < 0.05) control animals in progesterone concentrations from days 9-15 after ovulation. Our results support the hypothesis that large antral follicles in eCG-treated ewes exhibit distinctive echotextural characteristics. Follicular image attributes in eCG-treated ewes appear to be indicative of the changes in follicular morphology and secretory activity caused by the administration of the exogenous gonadotropin, which has both FSH- and LH-like activities.  相似文献   

5.
We have tested the hypothesis "that the ovulation rate in homozygous carriers (BB) and noncarriers (+2) of the Booroola FecB gene would not be different if the plasma concentrations of follicle-stimulating hormone (FSH) in the two genotypes were similar." For this purpose we used two experimental animal models: 1) the hypothalamic-pituitary disconnected (HPD) ovary-intact ewe; and 2) and GnRH agonist (i.e., Deslorelin)-treated ewe. Following HPD or Deslorelin treatment, the animals had low plasma concentrations of gonadotropins and were anovulatory. In both animal models, BB and +2 ewes were treated with exogenous pregnant mares serum gonadotropin (PMSG) and varying doses of FSH to induce preovulatory follicular growth, and human chorionic gonadotropin (hCG) to induce ovulation. HPD or Deslorelin-treated animals administered with pregnant mares serum gonadotropin without FSH followed by human chorionic gonadotropin failed to ovulate. However for both animal models, the proportion of BB and +2 ewes ovulating to various doses of FSH differed such that significantly greater proportions of +2 animals ovulated relative to the BB genotype (P < 0.05). When HPD or Deslorelin-treated BB and +2 ewes were administered identical doses of FSH, the mean ovulation rate and plasma concentrations of FSH in those animals which ovulated was the same in both genotypes. These findings confirm, at least in part, the aforementioned hypothesis. The results also demonstrated that higher ovulation rates were obtained in both genotypes as the FSH dose was increased. Collectively, these findings infer that the higher mean ovulation rate in normal intact BB ewes compared to the +2 genotype is attributable to effects of the FecB gene at the level of ovarian follicular development as well as at the level of pituitary FSH release.  相似文献   

6.
Two experiments were performed to determine the endocrine and ovarian changes in medroxyprogesterone acetate (MAP)-primed ewes after ram introduction. Experiment 1 was performed during the mid-breeding season with 71 ewes primed with an intravaginal MAP sponge for 12 days. While the control (C) ewes (n = 35) were in permanent contact with rams, the ram effect (RE) ewes (n = 36) were isolated for 34 days prior to contact with rams. At sponge withdrawal, all ewes were joined with eight sexually experienced marking Corriedale rams and estrus was recorded over the next 4 days. The ovaries were observed by laparoscopy 4-6 days after estrus. Four weeks later, pregnancy was determined by transrectal ultrasonography. In eight ewes from each group, ovaries were ultrasonographically scanned; FSH, LH, and estradiol-17beta were measured every 12 hours until ovulation or 96 hours after estrus. The response to the rams was not affected by the fact that ewes had been kept or not in close contact with males before teasing. No differences were found in FSH, LH, estradiol-17beta concentrations, growth of the ovulatory follicle, onset of estrus, ovulation rate, or pregnancy rate. Experiment 2 was performed with 14 ewes during the nonbreeding season. Ewes were isolated from rams for 1 month, and received a 6-day MAP priming. Ovaries were ultrasonographically scanned every 12 hours, and FSH, LH, estradiol-17beta, and progesterone were measured. Ewes that ovulated and came into estrus had higher FSH and estradiol-17beta levels before introduction of the rams than did ewes that had a silent ovulation. The endocrine pattern of the induced follicular phase of ewes that came into estrus was more similar to a normal follicular phase, than in ewes that had a silent ovulation. The follicle that finally ovulated tended to emerge earlier and in a more synchronized fashion in those ewes that did come into estrus. All ewes that ovulated had an LH surge and reached higher maximum FSH levels than ewes that did not ovulate, none of which had an LH surge. We conclude that (a) the effect of ram introduction in cyclic ewes treated with MAP may vary depending on the time of the breeding season at which teasing is performed; (b) patterns of FSH, and estradiol-17beta concentrations, as indicators of activity of the reproductive axis, may be used to classify depth of anestrus; and (c) the endocrine pattern of the induced follicular phase, which is related to the depth of anestrus, may be reflected in the behavioral responses to MAP priming and the ram effect.  相似文献   

7.
Involvement of insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) in ovarian folliculogenesis has been extensively studied during the last decade. In all mammalian species, IGF-I stimulates granulosa cell proliferation and steroidogenesis. The concentrations of IGF-I and -II do not vary during terminal follicular growth and atresia. In contrast, the levels of IGFBP-2 and -4, as well as IGFBP-5 in ruminants, dramatically decrease and increase during terminal follicular growth and atresia, respectively. These changes are responsible for an increase and a decrease in IGF bioavailability during follicular growth and atresia, respectively. They are partly explained by changes in ovarian expression. In particular, expression of IGFBP-2 mRNA decreases during follicular growth in ovine, bovine and porcine ovaries, and expression of IGFBP-5 mRNA dramatically increases in granulosa cells of bovine and ovine atretic follicles. Changes in IGFBP-2 and -4 levels are also due to changes in intrafollicular levels of specific proteases. Recently, we have shown that the pregnancy-associated plasma protein-A (PAPP-A) is responsible for the degradation of IGFBP-4 in preovulatory follicles of domestic animals. Expression of PAPP-A mRNA is restricted to the granulosa cell compartment, and is positively correlated to expression of aromatase and LH receptor. From recent evidence, the bone morphogenetic protein (BMP) family would also play a key role in ovarian physiology of domestic animals. In particular, we and others have recently shown that a non-conservative substitution (Q249R) in the bone morphogenetic protein-receptor type IB (BMPR-IB) coding sequence is fully associated with the hyperprolific phenotype of FecB(B)/FecB(B) Booroola ewes. BMP-4 and GDF-5, natural ligands of BMPR-IB, strongly inhibit secretion of progesterone by ovine granulosa cells in vitro, but granulosa cells from FecB(B)/FecB(B) ewes are less responsive than those from FecB(+)/FecB(+) to the action of these peptides. It is suggested that in FecB(B)/FecB(B) ewes, Q249R substitution would impair the function of BMPR-IB, leading to a precocious differentiation of granulosa cells and of follicular maturation. Interestingly, recent findings have described mutations in BMP-15 gene associated with hyperprolific phenotypes in Inverdale and Hanna ewes, suggesting that the BMP pathway plays a crucial role in the control of ovulation rate.  相似文献   

8.
Equine chorionic gonadotropin (eCG) is a member of the glycoprotein family of hormones along with LH, FSH and thyroid‐stimulating hormone. In non‐equid species, eCG shows high LH‐ and FSH‐like activities and has a high affinity for both FSH and LH receptors in the ovaries. On the granulosa and thecal cells of the follicle, eCG has long‐lasting LH‐ and FSH‐like effects that stimulate oestradiol and progesterone secretion. Thus, eCG administration in dairy cattle results in fewer atretic follicles, the recruitment of more small follicles showing an elevated growth rate, the sustained growth of medium and large follicles and improved development of the dominant and pre‐ovulatory follicle. In consequence, the quality of the ensuing CL is improved, and thereby progesterone secretion increased. Based on these characteristics, eCG treatment is utilized in veterinary medicine to control the reproductive activity of the cow by i) improving reproductive performance during early post‐partum stages; ii) increasing ovulation and pregnancy rates in non‐cyclic cows; iii) improving the conception rate in cows showing delayed ovulation; and finally, iv) eCG is currently included in protocols for fixed‐time artificial insemination since after inducing the synchrony of ovulation using a progesterone‐releasing device, eCG has beneficial effects on embryo development and survival. The above effects are not always observed in cyclic animals, but they are evident in animals in which LH secretion and ovarian activity are reduced or compromised, for instance, during the early post‐partum period, under seasonal heat stress, in anoestrus animals or in animals with a low body condition score.  相似文献   

9.
Two experiments were performed to determine the endocrine and ovarian changes in medroxyprogesterone acetate (MAP)-primed ewes after ram introduction. Experiment 1 was performed during the mid-breeding season with 71 ewes primed with an intravaginal MAP sponge for 12 days. While the control (C) ewes (n = 35) were in permanent contact with rams, the ram effect (RE) ewes (n = 36) were isolated for 34 days prior to contact with rams. At sponge withdrawal, all ewes were joined with eight sexually experienced marking Corriedale rams and estrus was recorded over the next 4 days. The ovaries were observed by laparoscopy 4–6 days after estrus. Four weeks later, pregnancy was determined by transrectal ultrasonography. In eight ewes from each group, ovaries were ultrasonographically scanned; FSH, LH, and estradiol-17β were measured every 12 hours until ovulation or 96 hours after estrus. The response to the rams was not affected by the fact that ewes had been kept or not in close contact with males before teasing. No differences were found in FSH, LH, estradiol-17β concentrations, growth of the ovulatory follicle, onset of estrus, ovulation rate, or pregnancy rate. Experiment 2 was performed with 14 ewes during the nonbreeding season. Ewes were isolated from rams for 1 month, and received a 6-day MAP priming. Ovaries were ultrasonographically scanned every 12 hours, and FSH, LH, estradiol-17β, and progesterone were measured. Ewes that ovulated and came into estrus had higher FSH and estradiol-17β levels before introduction of the rams than did ewes that had a silent ovulation. The endocrine pattern of the induced follicular phase of ewes that came into estrus was more similar to a normal follicular phase, than in ewes that had a silent ovulation. The follicle that finally ovulated tended to emerge earlier and in a more synchronized fashion in those ewes that did come into estrus. All ewes that ovulated had an LH surge and reached higher maximum FSH levels than ewes that did not ovulate, none of which had an LH surge. We conclude that (a) the effect of ram introduction in cyclic ewes treated with MAP may vary depending on the time of the breeding season at which teasing is performed; (b) patterns of FSH, and estradiol-17β concentrations, as indicators of activity of the reproductive axis, may be used to classify depth of anestrus; and (c) the endocrine pattern of the induced follicular phase, which is related to the depth of anestrus, may be reflected in the behavioral responses to MAP priming and the ram effect.  相似文献   

10.
The present study was conducted to evaluate superovulatory treatments in Awassi ewes by eCG and FSH. High number of unovulated follicles (P < 0.05) was observed in ewes treated with eCG in non-breeding season. It could be concluded that using FSH to induce superovulation in Awassi ewes is better than eCG.  相似文献   

11.
The aims of this study were to evaluate the chronology of periovulatory events (oestrus behaviour, LH surge and ovulation) in 16 superovulated Manchega sheep and to determine whether follicular status at start of the FSH supply might affect their occurrence. Mean timing for onset of oestrus behaviour was detected at 28.1 +/- 0.7 h after sponge withdrawal; the preovulatory LH surge and ovulation started at 37.2 +/- 0.7 h and 65.4 +/- 0.7 h after progestagen withdrawal, respectively. The intervals between oestrus, LH surge and ovulation were affected by a high individual variability, which might be the cause for reported decreased efficiency in embryo production. Current results also addressed the role of follicular status at start of the superovulatory treatment on the preovulatory LH surge and the ovulation. The interval LH surge-ovulation was increased in ewes with a growing dominant follicle at starting the FSH treatment (32.3 +/- 0.9 vs 28.6 +/- 0.5 h, p < 0.05). The developmental stage of the largest follicle at starting the superovulatory treatment also affected occurrence of LH surge and ovulation; follicles in growing phase advanced the occurrence of the LH surge and ovulation when compared to decreasing follicles (33.0 +/- 1.0 vs 43.5 +/- 1.1 h, p < 0.05, for LH peak and 60.7 +/- 1.1 vs 72.8 +/- 1.2 h, p < 0.05, for ovulation). Thus, only ewes with growing follicles ovulated prior to 55 h after sponge withdrawal; conversely, no sheep with decreasing follicles ovulated earlier than 67 h, when an 85.7% of the ewes bearing growing follicles has ovulated at 63 h.  相似文献   

12.
Maintenance of high levels of realized fertility (defined as the percentage of ewes that lamb) and appropriate levels of fecundity are critical for efficient sheep production. The optimal level of fecundity in most situations is well below the maximum attainable level and can be targeted by combining selection among and within breeds with use of an expanding array of single-gene mutations affecting ovulation rate and litter size. The heritability of litter size is approximately 0.10, allowing changes of up to 2%/year from simple mass selection. Mutations in several genes associated with the transforming growth factor β superfamily ( BMPRIB , GDF9 and sex-linked BMP15 ) can increase ovulation rates by 0.7–1.5 ova in heterozygous ewes. However, ewes that are homozygous for BMP15 or GDF9 mutations are sterile, so use of these mutations requires carefully structured breeding programmes. Improvements in fertility may be critical for autumn lambing or programmes that aspire to lamb throughout the year. Selection to improve fertility in spring matings has been successful; selected adult ewes have lambing rates of 80–85% in October and early November. The selected ewes have a dramatically reduced seasonal anestrus, and many ewes continue to cycle during spring and summer. Major genes affecting seasonal breeding have not been identified in sheep. Polymorphisms in the melatonin receptor 1a gene appear to be associated with seasonal breeding in some, but not all breeds. However, functional genomic studies of genes associated with circadian and circannual rhythms have potential to reveal additional candidate genes involved in seasonal breeding.  相似文献   

13.

The aim of this study was to evaluate the effect of a co-treatment of follicle-stimulating hormone (FSH) plus equine chorionic gonadotrophin (eCG) on serum insulin and insulin-like growth factor 1 (IGF-1) concentrations, superovulatory response, ovulatory rate, and number and production of embryos in Katahdin breed ewes during the non-breeding season. Twenty Katahdin ewes were synchronized with progestagens (CIDR) and assigned to two superovulation treatments (n = 10): (1): ewes treated with 200 mg ewe−1 of FSH from day 5 to 8 after CIDR insertion at decreasing doses every 12 h (FSH group) and (2) ewes treated as FSH group plus 300 IU of eCG on day 5 after CIDR insertion (FSH + eCG group). Estrous behavior was monitored and direct mating was performed. On days − 7 (CIDR insertion), 0 (CIDR withdrawal), and 7 (embryo recovery), blood samples were collected to determine serum hormone concentrations. Co-treatment with eCG (FSH group) did not affect (P > 0.05) serum hormone levels. Superovulation response, ovulation rate, recovery rate, fertilization, and number of embryos were also similar (P > 0.05) between treatments. Compared with FSH group, FSH + eCG ewes had lower (P < 0.05) number of transferable embryos and higher (P < 0.05) number of oocyte and a tendency to increase the number of degenerated embryos (P = 0.07). Overall results suggest that the administration of eCG is not beneficial either to improve the ovulatory response or the amount of transferable embryos in Katahdin ewes superovulated with a protocol using progesterone and FSH at decreasing doses.

  相似文献   

14.
Ewes from selected lines of sheep from each of two breeds, Finns (high ovulation rate, low ovulation rate and control lines with respective ovulation rates of 5.4, 2.7 and 3.3) and Merinos (T Merinos selected for increased ovulation rate and control Merinos with respective ovulation rates of 1.9 and 1.2) were used to examine how selection to alter ovulation rate had altered follicle development. Ovarian antral follicles were counted, measured, classified as nonatretic or atretic (more than five pyknotic bodies). The growth of ovulatory follicles in vivo, followed by repeated follicle ink marking, also was compared in the three lines of Finns. Regardless of breed, ewes selected for high ovulation rate had a similar number of antral follicles and a similar extent of atresia compared with their controls. Alterations induced by selection were located in the last stages of folliculogenesis. T Merinos exhibited a lower proportion of atretic follicles among follicles greater than 3 mm and a larger diameter of the largest healthy follicle when preovulatory follicles were excluded. High-line Finn ewes recruited more follicles, which produced smaller preovulatory follicles, each containing a smaller number of granulosa cells compared with either the low- or control-line ewes. Hence, physiological selection for high ovulation rate raised it by different methods in Merino than in Finn ewes.  相似文献   

15.
The aim of the study was to assess the effects of superovulatory treatment (multiple FSH‐dose vs single‐shot FSH treatment) and seasonality on embryo yields in fine‐wool Merino ewes. Treatment based on multiple FSH‐dose consisted of 200 mg of FSH (Folltropin®) administered in seven decreasing doses. Single‐shot treatment consisted of a single dose of 70 mg of FSH + eCG. In ewes treated with multiple FSH doses, number of recovered embryos was higher (6.0 ± 0.5 vs 3.5 ± 1.0), while non‐fertilization rate was lower (12.8 ± 3.9 vs 40.3 ± 9.5) during the breeding season when compared to the non‐breeding season (p < 0.05); although similar values of recovered Grades 1–2 embryos were observed between seasons. During the breeding season, proportion of responding ewes (98.1 vs 57.1%), ovulation rate (13.9 ± 0.8 vs 3.2 ± 1.2), recovered structures (7.9 ± 0.6 vs 1.7 ± 0.7), total recovered embryos (6.0 ± 0.5 vs 1.2 ± 0.6) and good‐quality embryos (5.1 ± 0.5 vs 0.9 ± 0.6) were higher for the multiple FSH‐dose treatment than for the single‐shot protocol. In a similar way, in the non‐breeding season, ovulation rate (11.3 ± 1.8 vs 6.0 ± 1.1) and recovered structures (6.6 ± 1.2 vs 2.7 ± 0.6) were higher for the multiple FSH injections protocol than those for the single‐shot treatment, resulting in higher recovered Grades 1–2 embryos (3.2 ± 0.9 vs 1.4 ± 0.5). Current results indicate that seasonal anestrus affected embryo yields when applying multiple FSH‐dose superovulatory treatment in Merino ewes, by decreasing the number of recovered embryos although the number of recovered good‐quality embryos was not affected. During both seasons, multiple FSH injections produced higher ovarian response and number of viable embryos than the single‐shot treatment.  相似文献   

16.
Dihydrotestosterone (DHT) induces follicular atresia under experimental conditions. However, whether it causes any antagonistic effect under natural condition is not known. In the present study, we investigated concentrations of DHT in follicular fluid and correlated them with concentrations of estradiol-17beta (E2) and its androgen substrates, androstenedione (A4) and testosterone (T), in healthy and atretic follicles of sheep. Merino ewes were treated twice with PGF2alpha (PG) to synchronize estrus. The ovaries were recovered at 14 days after the second PG (luteal phase) or 24h after the third PG given 14 days after the second PG (follicular phase). Follicles were dissected and their size and appearance were recorded. Follicular fluid was collected from follicles larger than 3.5mm and concentrations of E2, progesterone (P4), A4, T and DHT were determined by RIA. The inhibitory effect of DHT on conversion of T to E2 was tested in cultured granulosa cells. Appreciable levels of DHT were observed in the follicular fluid of ovine preovulatory follicles. The levels of DHT were much lower than those of E2, A4 and T, irrespective of physiological conditions of follicles. No difference was found in DHT concentration between healthy and atretic follicles. Dihydrotestosterone marginally inhibited aromatization of T in granulosa cells but this effect was only observed when the levels of DHT were 10 times higher than that of T in culture medium. These results indicate that DHT is present in ovine preovulatory follicles but its levels are not sufficient to exert any antagonistic effect on follicular development.  相似文献   

17.
乏情母牛50头、有周期活动母绵羊38头,超排处理引起发情后的4(羊)或7～8(牛)天摘取卵巢进行组织学研究。观察到排卵阻断的5种类型:(1)典型黄体但包含未排的卵母细胞,(2)由未破卵泡黄体化而形成的非典型黄体,(3)纤维性结缔组织团块,其中有散在性黄体细胞(仅见于牛),(4)具备葛拉夫氏泡典型结构的滞留卵泡,(5)颗粒膜已黄体化的滞留卵泡。50头牛中共有滞留卵泡(≥10mm)127个、正常黄体29个、非正常黄体20个。严寒和饥饿可能是卵泡囊肿普遍发生的主要原因。试验牛曾用18甲基炔诺酮药管处理9天。在植入和取出药管时各注射1次(共2次)PMSG的母牛,具有很高的(28/30)早期反应率(出现≥3个卵泡的母牛数/接受处理的母牛数),而仅在去管时1次注射PMSG者,反应微弱(4/20)。试验羊中,只有单一用FSH处理者,在发情当天血清E_2—17β浓度形成峰值(168.1pg/ml),而且正常黄体数亦略高(P<0.1)于用FSH加LH处理者。发情后4天血清P_4浓度则以后者为高(P<0.05)。绵羊滞留卵泡表现为孕酮优势,卵泡液中E_2—17β对P_4的浓度比为1∶46。  相似文献   

18.
The expression and concentration of follistatin and activin change during oestrous cycle suggesting their involvement in the regulation of follicular development. The aim of this study was to determine the level, source and potential role of follistatin in the sheep ovary. Follistatin in ovarian venous blood, measured by radioimmunoassay, remained at its low level from follicular phase (day ?1 and 0) to mid‐luteal phase (days 11–13) phase but were significantly elevated during the late luteal phase (days 14 and 15) when corpora lutea underwent regression. Western blot analyses of follicular fluid at day 15 of the cycle showed two strong bands at 42 and 45 kDa and weakly stained bands at 39 and 31 kDa. At day 0, these bands became weaker and the 39 kDa band became undetectable. However, there were no differences in follistatin concentrations between ovaries with and without functional corpus luteum (CL) during the whole luteal phase. In addition, although the ovaries of Booroola ewes normally contain more corpora lutea than those of normal merino ewes, follistatin concentrations in both jugular and ovarian venous blood were similar in Booroola and normal merino ewes. It is concluded that the secretion of follistatin from the ovary is not related to the formation of CL or high ovulation rate of Booroola ewes. The elevation in follistatin concentration in follicular fluid and ovarian blood during late luteal phase may indicate a dual role of follistatin in the luteolysis of existing CL and development of new follicle cohort.  相似文献   

19.
The professional application of agents to the manipulation of fertility of cows requires basic and applied knowledge of the physiologic mechanisms that are affected and of the pharmacologic agents that are used. In all areas of the pharmacologic manipulation of fertility, the achievement is less than the ideal, and further research is required to improve the efficiency of treatments. The induction of estrus in acyclic animals can involve a reduction in the depth of anestrus, pretreatment with progestagen to ensure estrous behavior and the formation of a normal corpus luteum, and then treatment with exogenous gonadotropin. Responsiveness to treatment can be variable and reflects the depth of anestrus of the animals. Improved treatment regimens require a knowledge of the basic mechanisms involved with the depth of anestrus, a means of assessing the depth of anestrus, and an understanding of the hormonal requirements of ovarian follicles for development and maturation in animals at different depths of anestrus. The optimal precision in the synchronization of estrus (and ovulation) in cyclic animals requires the synchronization of both follicular waves and the end of progestational phase. The end of progestational phase can be synchronized effectively using prostaglandin F2a (or analogs), or by treatment with progestagens with or without luteolytic agents. Procedures to synchronize follicular waves need to be established. The induction of superovulation can be achieved readily using gonadotropins prior to estrus synchronization using prostaglandin F2a. The responses to standard treatments in terms of ovulation rates and yield of transferable embryos are highly variable. The development of procedures to reduce this variability requires an understanding of the intra-ovarian mechanisms involved in recruitment of follicles for a wave of follicular growth, in the selection of dominant follicles for further development, and in the mechanisms controlling follicular atresia. Cystic ovarian disease can be treated effectively using HCG or GnRH (follicular cysts) or prostaglandin F2a (luteal cysts). The basic mechanisms resulting in failure of estrogen positive feedback on LH secretion (that results in cystic follicles) remain to be determined. Small but significant increases in pregnancy rates can be achieved treating cows with prostaglandin during the post-partum period, with prostaglandin to induce estrus for insemination, with GnRH or HCG at estrus, and with GnRH or progestagen treatment during diestrus. Beneficial effects of treatment have been shown in some trials but not in others.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   

20.
生殖激素控制卵泡细胞凋亡的研究进展   总被引：8，自引：0，他引：8  
研究表明颗粒细胞凋亡是导致卵泡闭锁的重要原因，而颗粒细胞凋亡涉及许多因素，其中生殖激素，如GnRH、FSH、LH、P4、E、A、GH、Mel、inhibin、activin、follistatin等间接地和直接地对卵巢卵泡细胞凋亡发挥重要的综合控制作用，因此正确理解激素对体内、外卵泡及颗粒细胞发育和衰亡的调节网络具有很重要的理论和实践意义。  相似文献   

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