In vitro histogenic capacities of limb mesenchyme from various stage mouse embryos☆

[摘要] Mesenchymecellsisolatedfrommouseembryoforelimbbuds(stages15through21)andplacedinhigh-densitymicromassculturesarecomparedwithrespecttotheirinvitrohistogeniccapacities.Particularemphasisisplacedonchangesininvitrochondrogeniccapacity.Stage15mouselimbculturesformnumerousaggregateswhichuniformlyfailtodifferentiateintocartilagenodules.Ontheotherhand,cartilagenodulesareobservedinculturespreparedfromallsubsequentstagelimbs,althoughthereisalineardecreaseinthesizeofnodulesbetweenstage16–17andmiddle-latestage21cultures.ThisdecreasecorrelateswithsimultaneousdecreasesinboththeproportionofaggregatingcellsandtheextentofdibutyrylcyclicAMP-stimulatedcartilageformation.Atthesametime,observationsindicatethattheproportionsofnonaggregatingandnonchondrogenicmesenchyme,myogeniccells,and,perhaps,fibrogenicmesenchymeareincreasing.Theonlyexceptionstothesepatternsareobservedinculturesfrommiddle-latestage21limbs,whencartilagedifferentiationinsituisalreadyextensive.Unlikeearlierstagecultures,whichformnearlyidenticalnumbersofaggregatesandnodules,middle-latestage21culturesformvariablenumbersofaggregates,onlyafewofwhichdifferentiateintocartilagenodules.Middle-latestage21culturesalsocontainunexpectedlylownumbersofmyogeniccells/unitareaofculture.Basedonchangesintheinvitrohistogeniccapacities,itisconcludedthatconcurrentwithaprogressionofmorphogeniceventsinthelimb,thereisaprogressionofchangesintherelativeproportionsofcellsubpopulations.Boththeexistenceofthedifferentsubpopulationsandthechangesintheirrelativeproportionscanbedetectedinvitro.Furthermore,itisconcludedthatcartilageformationinthelimbsofbothmouseandchickembryosprobablyoccursaccordingtoverysimilardevelopmentalprograms.

[学科分类] 生物科学（综合）