The relationship between cumulus cell-oocyte coupling, oocyte meiotic maturation, and cumulus expansion☆

摘要

Thetimingofthereductionofcumuluscell-oocytecouplingwascorrelatedwithoocytemeioticmaturationandtheexpansion(mucification)ofthecumulusoophorususingimmaturemicetreatedwithgonadotropins.Threehoursaftertheinjectionofanovulatorydoseofhumanchorionicgonadotropin(hCG),morethan90%oftheoocytesisolatedfromlargeGraafianfollicleshadundergonegerminalvesiclebreakdown,indicatingthatoocytemeioticmaturationhadbeeninitiated.However,nocumulusexpansionorreductionofintercellularcouplingwasdetectedatthistime.By6hrafterhCGinjection,theindexofoocyte-cumuluscellcouplingwasstillnotlessthanthatfoundinoocyte-cumuluscellcomplexesisolatedfromcontrolmicenotreceivinghCG.Cumulusexpansionat6hrpost-hCGwaslimitedtotheoutercumuluscellswhilethoseadjacenttotheoocytewerestilltightlypacked.Cumulusexpansionappearedcompleteby9hrafterhCGinjectionandthecumuluscell-oocytecouplingindexwasgreatlyreduced.Theseresultsshowthatoocytemeioticmaturationinthemouseisnotinitiatedbyareductionincumuluscell-oocytecouplingorbycumulusexpansion.However,theresultssuggestthatthereductionofintercellularcouplinginvivomaybearesultofcumulusexpansion.