Tissue interaction in chick liver development: A reevaluation: II. Parenchymal differentiation: Mesenchymal influence and morphogenetic independence☆

[摘要] Previousinvestigatorsofliverdifferentiationhavedescribeditsdependenceuponanepithelial-mesenchymalinteractionofpartialspecificity,basedupontheembryonicoriginofthemesodermalcomponent.Derivativesoftheventralmesodermencourageepithelialdifferentiation(PAS-detectableglycogensynthesis),whereasthoseofthedorsalmesodermdonot.Thepossibilityofacausalrelationshipbetweennormalhistogenesisandfunctionaldifferentiationwasnotexplored,butasuggestivecorrelationwasestablished.Thepresentstudyreinvestigatesthedevelopmentofhepaticfunction,reexaminingthenatureofthemesenchymalroleandtheapparentinterdependenceofdifferentiationandmorphogenesis.DifferentiationwasassessedbythecriterionofUDP-glucuronyltransferaseactivity.Theglucuronideproductwasmeasuredbyahighlysensitivespectrofluorometrictechniquefollowingitsisolationbythinlayerchromatography.Itisdemonstrated,inagreementwithpreviousstudies,thatdifferentiatedlevelsofspecializedfunctionareachievedonlyinthepresenceofmesenchyme,butthatthisneednotbethehomologousmesenchyme.Notallventrally-derivedmesenchymesarepermissiveinthisregard,however.Neitheristhereanyreasontobelievethatfavorablemesenchymesplayaninstructional,asopposedtoanutritionalrole.Augmentation,ratherthanacquisition,offunctionistheproductofthisinteraction.Functionaldifferentiationofhepaticendodermappearstorequireitscytologicalmaturation,butitshistologicalarchitectureisprobablyirrelevant.

[学科分类] 生物科学（综合）