Journal of reproduction and fertility. Supplement最新文献

{"title":"Control of GnRH secretion.","authors":"I. Clarke","doi":"10.1530/BIOSCIPROCS.9.001","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.001","url":null,"abstract":"During a discussion at the 1st International Symposium on Reproduction in Domestic Ruminants following Dr Gerald Lincoln's presentation, it became apparent that we needed a method to monitor gonadotrophin-releasing hormone (GnRH) secretion in sheep. Within the 6 years that have elapsed, three models have been developed for this purpose and it is now possible to monitor accurately the secretion of GnRH from the median eminence and to relate this to LH and FSH release We arc therefore able to conduct meaningful experiments to ascertain the roles of the various neural systems and feedback effects that might regulate GnRI-1 secretion. This paper will review the progress that has been made in measuring the secretion of GnRH, particularly in sheep, and consider steroidal feedback effects. Finally, brief consideration will be given to some of the various neural systems that might be involved in regulating GnRH secretion.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"62 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84777397","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":"In-vitro fertilization of ruminants.","authors":"N. First, J. Parrish","doi":"10.1530/BIOSCIPROCS.9.012","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.012","url":null,"abstract":"The first ruminant offspring from in-vitro fertilization was a bull calf born in 1981 (Brackett et aL, 1982). Since then, fertilization has been accomplished in vitro for the three domestic ruminants— cattle, sheep and goats. These developments are largely the result of recent advances in our understanding of oocyte maturation. sperm capacitation and embryonic development. It is the intent of this manuscript to address four questions concerning in-vitro fertilization with primary emphasis on cattle. The questions to be addressed are: (1) what are the uses or reasons for performing WE, (2) can it be done, (3) what are the relative efficiencies of each step and which steps need further development and (4) what are the physiological mechanisms through which the normal in-vivo or in-vitro fertilization process is accomplished.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"55 1","pages":"151-65"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91007928","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":"Detection of early pregnancy in domestic ruminants.","authors":"R. Sasser, C. Ruder","doi":"10.1530/BIOSCIPROCS.9.020","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.020","url":null,"abstract":"Tests for the detection of pregnancy early after insemination have not yet reached their full potential. Currently, the milk progesterone assay provides the earliest possible test, at an interval of one oestrous cycle after insemination, i.e. 17, 21 and 21 days in sheep, goats and cows respectively. This assay is pregnancy non-specific and rate of detection of pregnant animals is acceptable but less than desirable. Detection of activity of early pregnancy factor may develop into an excellent early test for many species, but the rosette inhibition test which is currently required has limited development and use. Pregnancy-specific protein B has been developed as a radioimmunoassay and is reliable under laboratory situations for ruminants. It can be used after 24 days of gestation in the cow. Application to field testing awaits development. Other pregnancy-associated or specific substances which are found in maternal body fluids might develop as pregnancy markers. Ultrasonic devices might provide very early detection in cattle but the expense of a test will limit application. All tests for pregnancy early after insemination have an inherent inaccuracy. Presence of an embryo at the time the test is applied will not assure pregnancy at the time of a confirmatory test, such as birth of live young or rectal examination in cows after 35 days of gestation. Therefore, no matter how early the test, a follow-up examination might be desirable in intensively managed herds or flocks. The animal industry is on the verge of new biotechnological approaches to reproductive management. The potential seems as great as the imagination.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"37 12 1","pages":"261-71"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82814584","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":"Luteal peptides and intercellular communication.","authors":"D. Schams","doi":"10.1530/BIOSCIPROCS.9.008","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.008","url":null,"abstract":"The variety of peptides synthesized by the corpus luteum (relaxin, vasopressin, oxytocin and oxytocin-related neurophysin) and their possible intracellular effects are reviewed. After luteinization of the granulosa cells and in response to LH and FSH, the output of oxytocin is increased. In addition, insulin-like growth factor is a very potent stimulus of oxytocin secretion. Although luteal cells respond to gonadotrophins by increased production of progesterone, there is no further secretion of oxytocin. Oxytocin is localized in large luteal cells which seem not to be under the direct control of gonadotrophins. Synthesis of luteal oxytocin seems to occur during the early luteal phase according to measurements of oxytocin mRNA. Highest tissue concentrations and secretion under in-vitro conditions were observed during the mid-luteal phase, and so synthesis, storage and secretion are unlikely to occur concomitantly. Under in-vitro conditions, oxytocin is secreted concomitantly with neurophysin and progesterone, and there appears to be some form of communication between small and large luteal cells for the secretion of progesterone and oxytocin under in-vivo conditions. Evidence has been obtained that oxytocin may have local effects in the ovary by inhibition of secretion (synthesis ?) of progesterone, especially during the early luteal phase. A mechanism can be suggested whereby, under physiological conditions, oxytocin may delay the increase of progesterone by inhibition of progesterone secretion and therefore delay down regulation of its own receptor. This would prolong the life-span of the CL and the oestrous cycle. Exogenous progesterone given on Days 1-4 shortens the cycle to about 12 days. The best evidence that oxytocin may be involved in controlling luteolysis comes from immunization experiments in ewes and goats, but there is no clear evidence of this type for cattle. Basal concentrations of oxytocin at the end of the luteal phase may interact with oxytocin receptors after the inhibitory effect of progesterone in the uterus is reduced, thus initiating synthesis of PGF-2 alpha.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"25 1","pages":"87-99"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82881223","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":"Use of chimaeras to study development.","authors":"G. Anderson","doi":"10.1530/BIOSCIPROCS.9.019","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.019","url":null,"abstract":"In Greek mythology a chimaera was a fire-breathing she-monster having a lion's head, a goat's body and a serpent's tail. Chimaeras have been used extensively as models for research in developmental biology under the more general definition of a composite animal or plant in which different cell populations are derived from more than one fertilized egg, or the union of more than two 2ametes (McLaren, 1976). This paper is limited to chimaeras produced by combination of cells from two or more mammalian embryos. Characteristics of chimaeras, methods for production and uses in research are described. Effort has been made to include results of direct relevance to domestic animals. Excellent reviews on mammalian chimaeras and their uses in research are available from McLaren (1976) and Le Douarin & McLaren (1984).","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"28 1","pages":"251-9"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79263519","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":"Photoperiodic control of the onset of breeding activity and fecundity in ewes.","authors":"D. Kennaway, E. Dunstan, L. Staples","doi":"10.1530/BIOSCIPROCS.9.014","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.014","url":null,"abstract":"The seasonal nature of fertility of sheep has been accepted for many years (Hafez, 1952). It has also placed major restraints on farmers wishing to maximize farm output Because sheep have a 5-month pregnancy and a 3-month lactation period it should be possible to produce 3 sets of lambs every 2 years. A major restraint on such a programme is the very strong seasonal photoperiodic influence upon fertility. In the farming systems of Europe there is a need to maximize the efficiency of labour-intensive management while in Australia there is a need to minimize labour-extensive farming systems. Both management strategies require better control of the onset of breeding activity In many areas of Australia the late autumn start of breeding of Suffolk. Romney. Border Leicester and Perindale ewes means that the lambs are often weaned at a time of deteriorating pasture quality in late spring/summer with subsequent poor weight gain. An earlier season would allow better growth of the lambs before the summer burn off. This review covers recent studies on the photoperiodic control of reproduction in ewes. We concentrate on evidence for the role of light, the pineal gland and melatonin on seasonal breeding in the ewe and discuss the ways this information has been used to gain control of sheep fertility and fecundity.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"70 1","pages":"187-99"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80301152","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":"Transgenic livestock.","authors":"J. Simons, R. B. Land","doi":"10.1530/biosciprocs.9.018","DOIUrl":"https://doi.org/10.1530/biosciprocs.9.018","url":null,"abstract":"Single genes can now be added routinely to the genome of mice by molecular manipulation as simple Mendelian dominants; this complements the normal process of reproduction to give 'transgenic' animals. Success in ruminants is limited to a few examples in sheep and although gene expression has yet to be documented, there is every reason to expect that it will be achieved. The application of this technology to livestock improvement depends on the identification of circumstances in which the phenotype is limited by the deficiency of a single protein. While there is little evidence to indicate that single dominant genes are in general likely to have favourable effects, it is argued that there are likely to be exceptions. These include particular combinations of promoter and structural gene sequences to alter feedback control, for example through a change in tissue specificity, and the alteration of definitive proteins such as those of milk. A mouse model has been established to study the molecular manipulation of sheep milk proteins. The sheep beta lactoglobulin gene has been incorporated and the sheep whey protein is secreted by the mammary gland of transgenic mice. For the future, means to delete or reduce the expression of existing genes are likely to be important, as are more effective means of incorporation such as retroviral based methods and the incorporation of multigene constructs. The resources required to test transgenic livestock will, however, be greater than those required to create them.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"44 1","pages":"237-50"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83555764","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 epididymis in bulls and rams.","authors":"R. P. Amann","doi":"10.1530/BIOSCIPROCS.9.010","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.9.010","url":null,"abstract":"","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"1 1","pages":"115-31"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89734818","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":"Gonadotrophic control of follicle growth in the ewe.","authors":"A. S. McNeilly, H. Picton, B. K. Campbell, D. T. Baird","doi":"10.1530/BIOSCIPROCS.2.014","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.2.014","url":null,"abstract":"Preovulatory follicle growth in the ewe is dependent on FSH although no precise relationship appears to exist between plasma concentrations of FSH and the number of preovulatory follicles which develop or ovulation rate. This may be related to a hitherto unrecognized influence of pulsatile LH on the growth of large follicles. Preovulatory follicle growth is dependent on the presence of basal amounts of LH, but pulsatile LH, while being essential to supply an increase in androgen substrate to the granulosa cells of the follicle, may also play a role in reducing the responsiveness of many large follicles to FSH, in particular during the preovulatory phase when plasma concentrations of FSH are reduced. Thus selection of the preovulatory follicle(s) may involve a previously unrecognized interaction between FSH and pulsatile LH secretion in which pulses of LH act in a negative rather than positive manner.","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"48 1","pages":"177-86"},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74325670","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":"A critique of the evidence on the importance of steroid feedback to seasonal changes in gonadotrophin secretion.","authors":"R. Goodman, F. Karsch","doi":"10.1530/BIOSCIPROCS.1.001","DOIUrl":"https://doi.org/10.1530/BIOSCIPROCS.1.001","url":null,"abstract":"Casual observation of farm animals immediately points to some basic differences in their reproductive function; namely, some species (sheep and horses) have distinct breeding seasons while others (cows and pigs) do not. The seasonal nature of reproduction in the former is not only of immense practical importance to the agricultural industry but is also of considerable theoretical interest to the reproductive endocrinologist. The demonstration that photoperiod is the primary environmental cue controlling reproduction in sheep (Yeates, 1949; Hafez, 1952) raises several intriguing questions including: How does the sheep measure the length of the day? How is photoperiodic information transferred from the photoreceptor to the hypothalamo— hypophysial axis? What changes in the hypothalamo—hypophysial axis determine the reproductive capacity of the gonads? In this paper we will concentrate on the last question. In both the ram (Pelletier & Ortavant, 1975b; Lincoln & Short, 1980) and the ewe (Legan, Karsch & Foster, 1977), photoperiodically controlled changes in the system governing the tonic mode of gonadotrophin secretion appear to be responsible for the seasonal transitions between reproductive activity and quiescence. During the breeding season tonic gonadotrophin secretion is high; in the non-breeding season it is low. In the male, these changes most probably provide a direct drive to the seasonal fluctuations in testicular function. In the female, however, the changes in tonic gonadotrophin secretion must operate via the luteinizing hormone (LH) surge system to cause the termination and re-initiation of oestrous cycles. More specifically, it has been proposed that oestrous cycles can occur only when tonic secretion of LH is sufficient to stimulate an oestradiol rise which is needed to induce the preovulatory LH surge. Ovarian cycles cease when tonic LH secretion is low because levels of the gonadotrophin are insufficient to produce the oestradiol signal for the LH surge (Legan et al., 1977). Details of this hypothesis and supporting evidence have been described by Legan & Karsch (1979) and Goodman & Karsch (1980). Although seasonal changes in tonic gonadotrophin secretion appear to be a critical element in both sexes, there is not general agreement as to how they are produced. In the ewe, the seasonal variation in tonic LH secretion is thought to reflect a change in responsiveness to the inhibitory feedback action of oestradiol. In the breeding season oestradiol is a weak inhibitory steroid whereas in anoestrus it is extremely potent in this regard (Legan et al., 1977). In contrast, it has been proposed that seasonal changes in LH secretion in the ram may not require sex-steroid feedback (Lincoln & Short, 1980). This question regarding the importance of sex-steroid feedback is not confined to the sheep. Indeed, it has been raised for numerous other seasonal breeders particularly birds (Follett, 1978) and hamsters (Turek & Campbell, 1979). Our inter","PeriodicalId":16956,"journal":{"name":"Journal of reproduction and fertility. Supplement","volume":"10 4","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72568244","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}