Reviews of reproduction最新文献

{"title":"Three-dimensional structure of the zona pellucida.","authors":"D P Green","doi":"10.1530/ror.0.0020147","DOIUrl":"https://doi.org/10.1530/ror.0.0020147","url":null,"abstract":"<p><p>The zona pellucida is the extracellular coat that surrounds the mammalian oocyte. It forms a spherical shell of remarkably uniform thickness (5-10 microns in eutherian mammals). The mouse is currently the largest source of data on the zona pellucida and this review is built largely on these data. The zona pellucida is composed of three proteins in both mice and humans: ZP1, ZP2 and ZP3. These proteins are glycosylated and, in mice, have mature relative molecular masses of 200,000, 120,000 and 83,000, respectively. ZP1 is a dimer of two apparently identical subunits. All three mouse proteins have been sequenced and possess transmembrane domains at their C-terminal ends coupled with furin cleavage sites immediately upstream. Sequence data have been used to provide an accurate assessment of the mole ratios of the three proteins. The ratio of ZP2:ZP3 is close to 1:1, whereas ZP1 is approximately 9% of the combined mole amounts of ZP2 and ZP3. Ultrastructural evidence suggests that the mouse zona pellucida is composed of filaments constructed by head-to-tail association of globular proteins. The coordinate synthesis of the three zona pellucida proteins coupled with the near 1:1 stoichiometry of ZP2 and ZP3 is consistent with a model in which ZP2-ZP3 heterodimers are the basic repeating units of the filament, with cross-linking of filaments by dimeric ZP1. This model is also consistent with data from ZP2 and ZP3 gene knockout and antisense experiments. However, the structure remains unproven. The small amount of ZP1 relative to ZP2 and ZP3 may have important implications for the distribution of ZP1 cross-links, since the number of cross-linking sites potentially exceeds the number of ZP1 dimer molecules by a considerable margin. The evidence that ZP1, ZP2 and ZP3 are all synthesized via a membrane-bound step is discussed and two models are proposed for the assembly of the zona pellucida. The cortical reaction and its effect on the zona pellucida are examined in detail. It is shown that the amount of material released by cortical granules could be of the order of 30% by mass of ZP1, and that if this material was distributed predominantly on the inner face of the zona pellucida, its local concentration could approach that of ZP1. A model in which the zona block to polyspermy is caused by direct titration of zona pellucida binding sites is suggested as an alternative to the explanation that relies on enzyme cleavage of ZP2 to ZP2f. Finally, some of the major experimental and structural issues that remain to be addressed are identified.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 3","pages":"147-56"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020147","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20344394","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":"Regulatory mechanisms in acrosomal exocytosis.","authors":"H Breitbart,&nbsp;S Rubinstein,&nbsp;Y Lax","doi":"10.1530/ror.0.0020165","DOIUrl":"https://doi.org/10.1530/ror.0.0020165","url":null,"abstract":"<p><p>Acrosomal exocytosis occurs after the binding of the spermatozoon to the zona pellucida of the oocyte via specific receptors. We suggest that the zona pellucida binds to at least two different receptors in the plasma membrane. One (R) is a Gi-coupled receptor that activates phospholipase C beta 1. The other (TK) is a tyrosine kinase receptor coupled to phospholipase C gamma. Binding to R would regulate adenylyl cyclase leading to an increase in cyclic adenosine monophosphate and protein kinase A activation. The protein kinase A activates a voltage-dependent Ca2+ channel in the outer acrosomal membrane that releases Ca2+ from the interior of the acrosome to the cytosol. This is the first (I), relatively small, rise in intracellular Ca2+ which leads to activation of the phospholipase C gamma. The products of phosphatidyl-inositol bisphosphate hydrolysis by phospholipase C, diacylglycerol and inositol-trisphosphate lead to protein kinase C translocation to the plasma membrane and its activation. Protein kinase C opens a voltage-dependent Ca2+ channel (L) in the plasma membrane, leading to the second (II), higher, increase in intracellular Ca2+ leading to acrosomal exocytosis. Spermine, a physiological constituent of the seminal plasma regulates sperm acrosomal exocytosis by modulating intracellular Ca2+ binding sites and phospholipase C activity. Spermine is rapidly incorporated into the sperm cells during ejaculation and temporarily inhibits premature capacitation and acrosome reaction. During the passage of the spermatozoon through the female genital tract, there is a progressive depletion of spermine from spermatozoa, so that capacitation and consequently the acrosomal exocytosis take place at the appropriate time, when the spermatozoon reaches the vicinity of the egg.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 3","pages":"165-74"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020165","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20344396","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":"Roles of reactive oxygen species in the regulation of luteal function.","authors":"H Kato,&nbsp;N Sugino,&nbsp;S Takiguchi,&nbsp;S Kashida,&nbsp;Y Nakamura","doi":"10.1530/ror.0.0020081","DOIUrl":"https://doi.org/10.1530/ror.0.0020081","url":null,"abstract":"<p><p>Ephemerality and prolongation of luteal function have been matters of great concern in reproduction for many years. However, their control mechanisms are very complex and differ among mammals. Recently, evidence has indicated that reactive oxygen species may play important roles in the regulation of luteal function. Reactive oxygen species are present in most somatic cells and are involved in apoptosis, or 'physiological cell death'. In the corpus luteum, reactive oxygen species also exert luteolytic effects as well as some paradoxical luteotrophic effects. This paper discusses the possible roles of reactive oxygen species in the control of luteal function.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 2","pages":"81-3"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020081","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20342407","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 culture of ovarian follicles.","authors":"G M Hartshorne","doi":"10.1530/ror.0.0020094","DOIUrl":"https://doi.org/10.1530/ror.0.0020094","url":null,"abstract":"<p><p>This review offers a practically oriented introduction to follicle culture in vitro, focusing on mouse follicles, but with reference to other species. The main principles of follicle growth are addressed, including the constraints of tissue culture, methods of follicle isolation, and techniques for individual and collective culture of intact follicles. Culture systems that support a spherical or a non-spherical follicular structure in vitro are discussed in terms of follicular and oocyte development, and methods for assessing follicular function in vitro are presented. Oocyte development in most in vitro culture systems is currently suboptimal and the parallel development of oocytes and follicles is discussed, with a view to maintaining the competence of the oocyte. Finally, some potential future applications of follicle growth in vitro are suggested.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 2","pages":"94-104"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020094","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20343047","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":"Environmental oestrogens--present understanding.","authors":"K J Turner,&nbsp;R M Sharpe","doi":"10.1530/ror.0.0020069","DOIUrl":"https://doi.org/10.1530/ror.0.0020069","url":null,"abstract":"<p><p>Three years ago it was hypothesized that the reported adverse changes in male reproductive health could be explained by exposure to compounds with oestrogenic (or other hormone disruptive) activity. Although this issue has been highly publicized, there has been little progress towards a realistic assessment of whether environmental oestrogens pose a health risk to humans. This article attempts to give a brief overview of the current status of knowledge concerning environmental oestrogens and highlights some of the difficulties associated with risk assessment. Compounds within several major groups of chemicals, including organochlorine pesticides, polychlorinated biphenyls, phenolic compounds and phthalate esters, have been identified as being weakly oestrogenic by in vitro and in vivo screening methods. Many of these compounds are widespread and persistent in the environment. They are likely to be present in the food chain, drinking water, plastics, household products and food packaging, although which is the most important route of human exposure is unclear. In addition to exposure to man-made chemicals, the consumption of plant-derived oestrogens in foodstuffs poses a potential risk to human health as phytoestrogens are more potent oestrogens and their intake by some infants is likely to be considerable.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 2","pages":"69-73"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20342405","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":"Adhesion molecules in implantation.","authors":"J D Aplin","doi":"10.1530/ror.0.0020084","DOIUrl":"https://doi.org/10.1530/ror.0.0020084","url":null,"abstract":"<p><p>At implantation, trophectoderm attaches to the apical uterine luminal epithelial cell surface. Molecular anatomy studies in humans and mice, and data from experimental models have identified several adhesion molecules that could take part in this process: integrins of the alpha v family, trophinin, CD44, cad-11, the H type I and Lewis y oligosaccharides and heparan sulfate. The endometrial cell surface mucin MUC1 may play a role in both steric inhibition of attachment and selective glycan display. After attachment, interstitial trophoblast invasion occurs requiring a new repertoire of adhesive interactions with maternal extracellular matrix as well as stromal and vascular cell populations. Human anchorage sites contain columns of cytotrophoblasts in which self-attachment gives way progressively to adhesion to extracellular matrix and then interstitial migration. The beta 1 integrins are important during these later stages of implantation and placentation.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 2","pages":"84-93"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020084","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20343046","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":"Fetal undernutrition and disease in later life.","authors":"D J Barker,&nbsp;P M Clark","doi":"10.1530/ror.0.0020105","DOIUrl":"https://doi.org/10.1530/ror.0.0020105","url":null,"abstract":"<p><p>Recent findings suggest that coronary heart disease and stroke, and the associated conditions, hypertension and non-insulin dependent diabetes, originate through impaired growth and development during fetal life and infancy. These diseases may be consequences of 'programming', whereby a stimulus or insult at a critical, sensitive period of early life results in long-term changes in physiology or metabolism. Animal studies provide many examples of programming, which occurs because the systems and organs of the body mature during periods of rapid growth in fetal life and infancy. There are critical windows of time during which maturation must be achieved; and failure of maturation is largely irrecoverable.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 2","pages":"105-12"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020105","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20343048","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":"Nuclear transfer and reprogramming.","authors":"T Kono","doi":"10.1530/ror.0.0020074","DOIUrl":"https://doi.org/10.1530/ror.0.0020074","url":null,"abstract":"<p><p>Nuclear transfer techniques for mammalian embryos have been developed in the last decade. Embryonic nuclei from advanced stages of preimplantation development can be fully reprogrammed and the totipotency is restored when nuclei are transferred into ooplasts. Transfer of nuclei after gene expression from the embryonic genome has started does not appear to restrict the reprogramming of these nuclei. The principles of nuclear transfer are outlined with respect to nuclear remodelling, nucleocytoplasmic interactions and effects of the cell cycle. However, the molecular mechanisms involved in reprogramming donor nuclei remain unknown. It is proposed that epigenetic DNA modification, such as DNA methylation that regulates gene expression, is related to the reprogramming of transplanted nuclei.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 2","pages":"74-80"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020074","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20342406","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":"Advances in understanding gonadotrophin-releasing hormone receptor structure and ligand interactions.","authors":"C A Flanagan,&nbsp;R P Millar,&nbsp;N Illing","doi":"10.1530/ror.0.0020113","DOIUrl":"https://doi.org/10.1530/ror.0.0020113","url":null,"abstract":"<p><p>Gonadotrophin-releasing hormone (GnRH) is the central regulator of the reproductive system and its analogues are used widely in the treatment of diverse diseases. The GnRH receptor is a member of the large family of G-protein-coupled receptors (GPCRs) which have seven transmembrane domains. Knowledge of these receptors has assisted the development of molecular models of the GnRH receptor that allow prediction of its three-dimensional configuration and the way GnRH binds and activates its receptor. Comparison with other GPCRs led to the discovery that Lys121, in the third transmembrane domain, has a role in agonist binding. The history of GnRH structure-activity studies has allowed the identification of an acidic residue in the third extracellular loop of the receptor that is required for binding of mammalian GnRH, while synthetic GnRH analogues have showed that Asn102, in the second extracellular loop, may interact with the carboxy-terminus of GnRH. These residues can now be incorporated into the receptor models that are being used to design orally active non-peptide GnRH analogues for contraception and treatment of a variety of reproductive disorders.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 2","pages":"113-20"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020113","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20343049","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":"Preimplantation growth factor physiology.","authors":"P L Kaye","doi":"10.1530/ror.0.0020121","DOIUrl":"https://doi.org/10.1530/ror.0.0020121","url":null,"abstract":"<p><p>The robust independence of preimplantation embryo development in vitro suggests that the developmental programme is autonomous. The rapid accumulation of evidence during the last decade for participation of many hormones, growth factors and their receptors in these early stages of embryogenesis has challenged this conclusion. In this review, the insulin and epidermal growth factor families, which have been best studied in mice, are used to illustrate the different roles growth factors may play in preimplantation physiology and the circuits that possibly mediate their participation. Tumour necrosis factor alpha, an inhibitory factor and growth hormone previously considered to be restricted to orchestrating postnatal growth and development, is also discussed. In the absence of results indicating the existence of a master regulatory factor, the data support the hypothesis that the redundancy of growth factor actions may provide fail-safe protection to the preimplantation developmental programme.</p>","PeriodicalId":79531,"journal":{"name":"Reviews of reproduction","volume":"2 2","pages":"121-7"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1530/ror.0.0020121","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20343050","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}