ISSN:1059-910X    

DOI:10.1002/jemt.1070270202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractFollicular development in the mammalian ovary is a complex process regulated by an orchestrated action of the pituitary gonadotropins, e.g., follicle stimulating hormone (FSH) and luteinizing hormone (LH), and local ovarian factors, such as peptide growth factors and steroids. The mechanism of endocrine/paracrine/autocrine regulation of folliculogenesis (i.e., cell proliferation and functions) has been addressed largely by biochemical means. However, the availability of immunological and molecular tools now enables us to undertake critical microscopic studies revealing the ovarian cell‐type specific synthesis and/or accumulation of many of these local peptide modulators, their roles in the proliferation and differentiation of follicular cells, and their regulation by gonadotropins and local factors. The objective of this review is to provide a comprehensive yet complete picture of the endocrine/autocrine regulation of mammalian folliculogenesis as revealed by microscopic studies. Efforts have been made to include adequate research information relevant to update our understanding of the process of follicular development; however, to maintain the brevity, many equally important studies could not be included. This review confirms that FSH and LH are still the primary stimuli for follicular development. However, it is clear that the actions of these hormones at the cell level involve a host of peptide factors which are produced locally by different follicular cell types and which are powerful modulators of gonadotropin actions. The temporal and spatial expression of the genes of these modulators, the synthesis of active factors, their interactions, and the dynamics of their receptors on the follicular cell surface may be the ultimate determinants of cellular events which are crucial to coordinated growth and differentiation of follicular cells leading to folliculogenesis and ovulation. © 1994 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070270203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe termparacrine controlhas recently become very fashionable in the field of endocrinology: however, no study has yet clarified directly the role of paracrine activity in the functional and morphological development of endocrine organs. We developed a culture system in which two types of cells were allowed to attach to opposite sides of a collagen membrane in order to observe cellular communication directly and used it to explore the role of granulosa and theca cell interactions in ovarian structure and function.In the first series of the study, we explored the interaction between theca and granulosa cells by investigating the morphology, proliferation, and steroidogenesis of the cells. Granulosa cells cultured alone were flattened and polygonal in shape and formed a monolayer sheet. Granulosa cells cocultured with theca cells formed multilayer sheets. The apical surface of each cell appeared convex. Numerous filopodia spread over the cellular surfaces to connect individual cells. Theca cells cultured alone were thin, flat, and spindle‐shaped. Theca cells cocultured with granulosa cells were also spindle‐shaped; however, the apical surface appeared convex. The cell numbers of both granulosa and theca cells in the cocultured group increased approximately twofold compared to control cells cultured alone. The progesterone producing activity of granulosa cells in the cocultured group was reduced to 40% of that of cells in the control group. In contrast, the androstenedione producing activity of theca cells in the cocultured group increased approximately threefold compared to that of control group cells.In the second series of experiments, effects of cellular communication on cellular response to gonadotropins were investigated. When granulosa cells were cultured with theca cells, FSH treatment (1 μg/ml) promoted cellular growth: however, LH treatment (1 μg/ml) suppressed cellular growth and augmented their progesterone production. In contrast, such effects of gonadotropins were not detected when granulosa cells were cultured alone. LH induced estradiol production by granulosa cells both cultured alone and cocultured with theca cells: however, FSH‐induced estradiol production was not detected in this experimental condition. LH treatment increased androstenedione production of theca cells cocultured with granulosa cells, but no increase was observed for theca cells cultured alone.These results demonstrate that communication between these two types of follicular cells results in reciprocal modulation of their morphology, structure, growth, and function and that the actions of gonadotropins on target cells in the follicular wall can also be modified by the communication between these cells. In contrast to granulosa and theca cells cultured alone, cells in coculture seemed to possess morphological and functional characteristics more similar to those of cells in the growing follicular wall in vivo. Therefore, we speculate that interactions between these two types of follicular cells is essential in the maintenance of original structure and function of the bovine follicular wall. © 1994 Wiley

ISSN:1059-910X    

DOI:10.1002/jemt.1070270204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractGranulosa cells, which nurse the oocyte and serve as a major source for estradiol and progesterone production, undergo major morphological changes which correlate very well with modulation of their steroidogenic capacity. These include changes in intercellular contacts and communication, in cell membrane receptors, and in the development and organization of organelles associated with steroidogenesis (i.e., mitochondria, smooth endoplasmic reticulum, lipid droplets, and lysosomes). These biochemical and morphological changes can also be obtained in primary cultures as well as in oncogene transformed granulosa cell lines established recently in our laboratory. A growing body of evidence suggests that plasticity of the cytoskeleton plays a major role in the biochemical and morphological differentiation of granulosa cells as well as in other steroidogenic cells. © 1994 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070270205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractElectron and fluorescence microscopic techniques have been used in a complementary fashion to study the patterns of follicle cell‐oocyte interactions within cumulus‐oocyte‐complexes of various mammals. The principal findings are: (1) two distinct types of transzonal processes exist that are distinguishable on the basis of cytoskeletal composition; (2) in some of the species examined (pig, goat, primate), corkscrew‐shaped processes rich in tubulin, traverse the zona pellucida and are invaginated into the oocyte cortex; (3) actin‐rich processes either ramify as a network at the outer surface of the zona pellucida or penetrate the zona and make contact with the oolemma in a species specific manner. These results are discussed with respect both to the need to employ complementary optical methods in assessing connectivity patterns within COC and to the possible role that extracellular matrix‐cell interactions play in the homeostatic control of oocyte growth and maturation. © 1994 Wil

ISSN:1059-910X    

DOI:10.1002/jemt.1070270206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractMammalian oogenesis is a process which requires a variety of changes in the structure and function of the specialized female germ cell. Evidence suggests that the cytoskeleton may mediate several of these structural and functional changes. In this review we evaluate what is known of cytoskeletal function during oogenesis, with emphasis on specialized cytoskeletal features in mammals. Existing investigations suggest that the oocyte, as a highly specialized cell, contains unique cytoskeletal elements which exhibit functions restricted to the process of early development. © 1994 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070270207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper reviews the process of peri‐ovulatory oocyte maturation and the ultrastructural organization of the human egg and compares it with that of the mouse. The main thrust of the paper is on the human, since there are several reviews on the mouse. Both preovulatory and postovulatory events at fertilization, as well as some of the aberrant features of maturation are covered. Some changes induced by oocyte culture and cooling in the human are also included. The report attempts to focus on unique features of the human oocyte and shows a variety of ultrastructural differences between human and murine oocytes, which may well reflect differences in their physiology and biochemistry. Based on these differences and further observations on the process of fertilization of both species, particularly with respect to the inheritance of paternal centrioles, it is concluded that the mouse may not be a suitable modle for the development and refinement of current procedures in human assisted reproductive technology. © 1994 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070270208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThis study examined the effects of cryopreservation on cellular organization, chromosomal complement, and developmental potential of immature and mature mouse and human oocytes. Chromosomal analyses were performed by DNA fluorescence microscopy and karyotyping on the same metaphase II‐stage oocytes before and after freezing. Cellular analyses involved electron microscopy, time‐lapse video recording, and fluorescent‐probe microscopy of cortical granules. The findings demonstrate that while profound cytoplasmic, nuclear, and nucleolar alterations occur in the immature oocyte during cryopreservation, an apparently normal nucleus and cytoplasm is re‐established progressively after thawing and culture. The resulting oocytes mature at high frequency and for the mouse, are fertilizable and capable of normal preimplantation of embryogenesis. Cryopreservation of mature mouse and human oocytes is not accompanied by a significant increase in the frequency of aneuploidy. However, cryopreserved human oocytes, while fertilizable, arrest development during the early cleavage stages and display aberrant patterns of cytokinesis. The possible etiologies of developmental failure in the human embryo that may be related to oocyte cryopreservation, as well as the potential benefits of cryopreservation of the immature oocyte, are discussed with respect to clinical and commercial applications. © 1994 Wiley

ISSN:1059-910X    

DOI:10.1002/jemt.1070270209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070270210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070270201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY