Journal of reproduction and fertility. Supplement最新文献

{"title":"Spermatogenesis and Sertoli cell numbers and function in rams and bulls.","authors":"H. Mt, C. Monet-Kuntz, M. Courot","doi":"10.1530/BIOSCIPROCS.9.009","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.009","url":null,"abstract":"The two main types of cellular associations (type I, 2 generations of spermatocytes + 1 of spermatids; type II, 1 of spermatocytes and 2 of spermatids) occupy, respectively, more than half and about a third of the seminiferous epithelium cycle in rams and bulls. However, the duration of the cycle of the seminiferous epithelium and that of spermatogenesis differ between the species. A1 spermatogonia and Sertoli cell total numbers are highly correlated in adult rams and bulls. Mitosis in Sertoli cells occurs mostly in utero but may still occur for a short period after birth. Between birth and puberty there is about a 5-fold increase in the number of Sertoli cells. After that there are no seasonal- or age-related increases in the number of adult Sertoli cells. Some factors (season of birth; nutrition; genetics; hormones) affect mitosis of Sertoli cells in prepubertal animals. Sertoli cells differentiate after cessation of mitosis. Their differentiation is affected by cryptorchidism, nutrition, genetics and hormones. Their adult function is only poorly known. ABP and rete testis fluid secretions and nuclear Sertoli volume fluctuate under the influence of the same factors, but they are not always linked together. This reinforces the need for more knowledge of Sertoli cell secretions and function.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"12 1","pages":"101-14"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82413053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neurotransmitter regulation of luteinizing hormone and prolactin secretion.","authors":"R. Dailey, D. Deaver, R. Goodman","doi":"10.1530/BIOSCIPROCS.9.003","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.003","url":null,"abstract":"","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"70 1","pages":"17-26"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80978820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Endocrine regulation of puberty in cows and ewes.","authors":"J. Kinder, M. Day, R. Kittok","doi":"10.1530/BIOSCIPROCS.9.013","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.013","url":null,"abstract":"Sexual maturation in cows and ewes is modulated through changes in hypothalamic inhibition. This inhibition results in little or no stimulation of the release of gonadotrophins from the anterior pituitary. The ovary has a primary role in inhibiting gonadotrophin secretion during the prepubertal period and the responsiveness to the negative feedback effects of oestrogen decreases during the peripubertal period. There is also an increased secretion of ovarian progesterone during the peripubertal period but its role in the process of sexual maturation is not clear. Photoperiodic cues and dietary intake act upon the hypothalamus to modulate gonadotrophin secretion during sexual maturation and, in turn, influence the time when puberty occurs.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"1 1","pages":"167-86"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74152597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expression of the genes encoding bovine LH in a line of Chinese hamster ovary cells.","authors":"J. Nilson, D. Kaetzel","doi":"10.1530/BIOSCIPROCS.9.017","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.017","url":null,"abstract":"Synthesis of biologically active LH is complex, due in part to its heterodimeric subunit structure and to the numerous post-translation modifications of each subunit. Through the use of mammalian expression vectors we have been able to introduce the bovine alpha subunit and LH-beta genes into a Chinese hamster ovary cell line deficient in dihydrofolate reductase. The bovine genes are actively expressed and the Chinese hamster ovary cells secrete biologically active LH. The expression vector containing the bovine alpha subunit gene also contains a modified mouse gene encoding dihydrofolate reductase, permitting the use of methotrexate to amplify selectively the bovine alpha subunit gene after its integration into the genome of the Chinese hamster cells. This provides a novel means for assessing the importance of alpha subunit concentration with respect to assembly of the heterodimer. In addition, methotrexate selection leads to the over-production of LH (10 micrograms/10(6) cells/24 h). Finally, because the bovine LH produced in the Chinese hamster ovary cells is glycosylated, this transfection system can be used in conjunction with in-vitro mutagenesis to determine whether site-specific changes in glycosylation have an effect on subunit assembly and biological activity. This transfection approach therefore offers multiple avenues to explore further the molecular mechanisms underlying the complex biosynthetic pathway of bovine LH.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"108 1","pages":"227-36"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80533167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Searching for an inhibitory action of blood-borne beta-endorphin on LH release.","authors":"P. Malven","doi":"10.1530/biosciprocs.9.002","DOIUrl":"https://doi.org/10.1530/biosciprocs.9.002","url":null,"abstract":"Concentrations of beta-endorphin were quantified in peripheral blood plasma of sheep by a radioimmunoassay that cross-reacted with beta-lipotrophin. Plasma concentrations of beta-endorphin increased abruptly after physical confinement, bacteraemia, and electroacupuncture treatment for induction of analgesia. In these experimental situations in which plasma concentrations of beta-endorphin increased, plasma concentrations of LH often decreased. To test the hypothesis that increases in blood-borne beta-endorphin actually caused the decrease in LH release, naloxone was administered to antagonize the opioid receptors at which blood-borne beta-endorphin might act. In no case did administration of naloxone disrupt the temporal correlation between experimentally induced increases in plasma beta-endorphin and decreases in plasma LH. It was concluded that the increases in blood-borne beta-endorphin did not cause the decrease in LH release. Other research investigated whether beta-endorphin might be delivered via blood from pituitary to hypothalamus in locally enriched concentrations. Even when pituitary release of beta-endorphin was acutely stimulated, it was not possible to demonstrate retrograde delivery of beta-endorphin to the hypothalamus without dilution in the systemic circulation. In conclusion, it is unlikely that blood-borne beta-endorphin inhibits the release of LH, and beta-endorphin should not be classified as a hormone until blood concentrations of the peptide can be shown to exert some effect at a location distant from its site of secretion.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"3 1","pages":"9-16"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90165350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Short light cycles induce persistent reproductive activity in Ile-de-France rams.","authors":"J. Pelletier, G. Almeida","doi":"10.1530/BIOSCIPROCS.9.016","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.016","url":null,"abstract":"European breeds of rams appear to be responsive to photoperiodic changes even though there are large differences between breeds in the timing and amplitude of endocrine (LH and testosterone) and gametogenetic variations before the sexual season. Light regimens such as 6-month light cycles or alternations of constant short and long days every 12-16 weeks are able to entrain the parameters of sexual activity. In these regimens in which the period of the light cycle is shortened, LH release is markedly stimulated during decreasing daylength and evidence is presented, from the relationship of LH and testosterone patterns, that the dampening of LH stimulation could simply result from the effect of steroid feedback. However, there is a gap of several weeks between the maximum LH and testosterone concentrations during which testis growth occurs. Experiments were conducted with Ile-de-France rams, markedly seasonal breeders, in which the period of the light cycle was decreased, in different groups of animals, from 6 to 4, 3, 2 or 1 month. Rams submitted to the three light regimens with the longest periods presented testicular variations which paralleled those of the photoperiod, but those kept in the two regimens with the shortest periods had a progressive increase in testicular weight up to the maximum value (300-350 g) with no further major changes. Therefore, in rams kept in 2-month light cycles, testicular weight remained constant for twelve successive cycles (2 years). LH and testosterone plasma measurements indicated that LH was sufficiently stimulated to maintain testicular development during each decreasing daylength phase but that the stimulation was shifted before testosterone could reach levels at which feedback effects could be exerted. However, all the measures of sperm production were at values characteristic of the sexual season. Similar testicular weight maintenance was also obtained in rams submitted to a regimen in which short days (8L:16D) alternated every month with a split photoperiod interpreted as a long day (7L:8D:1L:8D). It is concluded that short light cycles are able to induce persistent reproductive activity in Ile-de-France rams, which may have practical applications in sheep production systems.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"11 1","pages":"215-26"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78286653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Function of the hypothalamic-hypophysial axis during the post-partum period in ewes and cows.","authors":"T. Nett","doi":"10.1530/BIOSCIPROCS.9.015","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.015","url":null,"abstract":"During pregnancy the hypothalamic-hypophysial axis is suppressed by the high concentrations of progesterone and oestradiol in the circulation. The high concentrations of these steroids appear to inhibit secretion of GnRH from the hypothalamus, resulting in inadequate stimulation of pituitary gonadotrophs to maintain synthesis of LH. This produces a depletion of LH in the anterior pituitary gland that must be restored after parturition before normal oestrous cycles can begin.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"38 1","pages":"201-13"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74276628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of follicular growth and development.","authors":"J. Ireland","doi":"10.1530/BIOSCIPROCS.9.005","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.005","url":null,"abstract":"During folliculogenesis a group of growing preantral follicles becomes responsive and dependent upon gonadotrophins, especially FSH, for their continued growth and differentiation. However, most of these follicles undergo atresia. The mechanisms that result in survival of a specific number of ovulatory (dominant) follicles appear to depend upon: (a) responsiveness of preantral follicles to gonadotrophins, (b) inhibitory and stimulatory factors from a dominant follicle, and (c) an exquisitely sensitive long-loop feedback system between the dominant follicle and pituitary gland.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"15 1","pages":"39-54"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76943034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in sperm surfaces associated with epididymal transit.","authors":"R. Hammerstedt, J. Parks","doi":"10.1530/BIOSCIPROCS.9.011","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.011","url":null,"abstract":"","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"29 1","pages":"133-49"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74093984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regulation of the secretion of FSH in domestic ruminants.","authors":"J. Findlay, I. Clarke","doi":"10.1530/BIOSCIPROCS.9.004","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.004","url":null,"abstract":"In the past 2-3 years there have been considerable advances in our understanding of thc neuroendocrine processes controlling pituitary function (Clarke, 1987) and the nature of steroidal and non-steroidal feedback regulation, particularly by the gonadal peptide. inhibin (Findlay, 1986). These advances offer new insights into the regulation of gonadotrophin secretion and gonadal function, and could have a considerable commercial impact in animal industry. In this review, we summanze these advances with respect to the control of FSH secretion in sheep and cattle.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"205 1","pages":"27-37"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83573459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}