Mechanism Of Mouse Oocyte IVM Induced By FSH

Regulation mechanism of growth, development and maturation of oocyte in mammal was one of foci of reproductive biology and developmental biology. Gonadotropins, especially FSH, played a important role in maturation of oocyte. There were two hypotheses on mechanism of meiotic resumption presently, one was cumulus oophorus expanded which induced by gonadotrophin breaked gap junctional communation between oocyte and granulosa cells, blocked the conduction of meiosis-inhibitiory signals from the outer cumulus cells to the oocyte, then meiotic resumption. The other was meiotic resumption by eliciting a maturation-inducing signal from the granulosa cells which overrided the inhibitory milieu of the follicle. However, property and regulation mechanism of the positive factor were still unknown. People made a great progress in IVM in mammal recently, even though maturation of oocyte in some species were still very low. Many problems about IVM were still remained. In assisted reproduction technology program of human and endangered species, oocyte obtaining was very difficult. It is nessary to use oocyte maximumly. Several studies reported culumus cells produced some positive factors which could influence maturation. So we use mouse as a model, to investigate the function of these factors, to improve maturation and development of PNO and NO at GV stage. Development of mammalian oocytes was a series of complex and developmentally regulated process. Gap junctional communication and paracrine signaling Interplay in those processes. Which kind of communication dominated in meiotic resumption was unknow. This study was to investigate the path way and the effect of the positive factors by using the gap junctional inhibitor and co-culture technique to provide basic data for maturation and development of oocyte in cumulus cell co-culture system. The results obtained were as follows: 1. Dissociated cumulus cells produced some meiosis-inducing factors which could act as a paracrine signal. 2. Dissociated cumulus cells produced some factors, but the factors could not induce meiotic resumption of oocyte in COCs. 3. The action of positive meiosis-inducing factors secreted by FSH-stimulated cumulus cells on oocyte depended on gap junctional communication which was dominant manner in meiosis resumption. 4. FSH-stimulated dissociated cumulus cells from swine produced some factors which could increase the percentage of GVBD of PNO and NO, but not improve percentage of fertilization and blastulae in mouse.