Cell shape and membrane changes in the eight-cell mouse embryo: Prerequisites for morphogenesis of the blastocyst☆

[摘要] Attheeight-cellstage,theblastomeresofthepreimplantationmouseembryoundergoadramaticshapechange,compaction,whichisconsideredessentialtothefuturesegregationofpresumptivecelltypes.Thisinvestigationdemonstratesthatcompaction1)occursinvivo,2)isaccompaniedbytheformationoftightandgapjunctionsand3)canbereversiblyinhibitedinvitrobycalcium-depletedmediumandalsobycytochalasinB(CCB).Althoughmicrotubulesfrequentlyareobservedincorticalregionswherecompactionisproceeding,colcemidandcolchicinehavenoinhibitoryeffect.Calcium-freemediumandCCBdissociatecompactedembryos,over50%ofwhichrecoverinnormalmediumin3and0.25hr,respectively.TheCa2+thresholdforcompactionisapproximately0.1–0.2mMandmayberequiredfornormalintercellularadhesions.Sincecompactionmarksthebeginningoftightjunctionformationandprovidesthenecessarycell-to-cellappositionforthedevelopmentofthezonulaoccludensatthemorulastage,itisconsideredtobetheinitialstepinblastocystmorphogenesis.Inaddition,thisinvestigationprovidesthemeanstoreprogramcompactionbyreversibleinhibitionandtherebystudytheoriesofcelldetermination.

[学科分类] 生物科学（综合）