Metabolic coupling, cumulus expansion and meiotic resumption in mouse cumuli oophori cultured in vitro in the presence of FSH or dcAMP, or stimulated in vivo by hCG

Publisher Website
Google Scholar
Abstract
The temporal changes of metabolic coupling between the mouse oocyte and the cumulus cells which follow hCG [human chorionic gonadotropin] injection in vivo and FSH treatment in vitro were studied by measuring what fraction of [3H]uridine taken up by cumulus cells was transferred to the oocyte. Meiotic resumption and a partial coupling loss (to 35% of the initial value) spontaneously occurred in cumuli cultured in control medium. The addition of 1 .mu.g FSH/ml in vitro, or the injection of hCG in vivo caused a delay of about 3 h in both phenomena and a near total uncoupling, together with cumulus expansion. FSH caused uncoupling even if cumulus expansion was prevented by the addition of heparin. The presence of 2 mM-d[dibutyryl]cAMP prevented meiotic resumption in cumulus-enclosed oocytes and maintained a high level of cooperation for at least 6 h. The slow uncoupling observed at later times was due to cumulus expansion, because it was totally prevented by heparin. Metabolic cooperation with the cumulus oophorus and meiotic resumption could be both regulated by FSH through variations of intracellular levels of cAMP.