Recombinant bovine growth hormone stimulates nuclear maturation of bovine oocytes in vitro and promotes subsequent embryonic development.

摘要

When cumulus-oocyte complexes (COCs) and cumulus-free oocytes were cultured in modified Medium 199 supplemented with 0, 0.1, 1, 10, 100 or 1000 ng/ml recombinant bovine growth hormone for 24 h, no cumulus expansion was observed in most COCs in the presence of any of the tested concentrations of growth hormone. The efficacy of nuclear maturation of oocytes to metaphase II was better promoted by growth hormone in COCs treated with 10-1000 ng/ml (77-78%) than in those treated with 0-1 ng/ml (57-64%).When COCs were cultured in the presence or absence of 10 ng/ml growth hormone for 0-9 h, the proportions of oocytes that reached prometaphase I and metaphase I after 6 and 9 h of culture respectively were higher in the presence (53 and 51%) than in the absence (34 and 30%) of growth hormone. After in vitro maturation and fertilization, no differences were observed in the penetration rate (82-91%), pronuclear formation (27-45%) and polyspermy (23-29%) 8 h after insemination among cumulus-enclosed oocytescultured in the presence of different concentrations (0-1000 ng/ml) of growth hormone. When, starting 8 h after insemination, oocytes were cultured for 136 h in a chemically defined medium, 21-25% developed to the morula stage or beyond, no effect of the different concentrations of growth hormone during oocyte maturation being apparent. However, 192 h after insemination higher proportions of oocytes developed to the blastocyst stage when COCs were matured in the presence (13-15%) than in the absence (6%) of 10-1000 ng/ml growth hormone.