Two distinct regulatory steps in cartilage differentiation☆
[摘要] Theeffectofdevelopmentalstageonchondrogeniccapacityinhigh-densitycellculturesofchickembryonicwingbudmesenchymeisexamined.Mesenchymefromstage19embryosformsaggregatesofcloselyassociatedcellswhichdonotformcartilagematrix,norcontainsignificantlevelsoftypeIIcollagenthataredetectablebyimmunofluorescence,unlesstheyaretreatedwithdibutyrylcyclicAMP.Mesenchymefromstage24embryonicwingbudsinhigh-densitycellcultureswillspontaneouslyformcartilage,asdefinedbyelectronmicroscopyandimmunofluorescencewithantibodytotypeIIcollagen.Culturespreparedfromstage26wingsformnumerousaggregateswhichfailtoaccumulateanAlcianblue-stainingmatrixandwhichresemblemesenchymecellsmorphologically.However,becausethesecellsshowconsiderableintracellularimmunofluorescencefortypeIIcollagen,theyareactuallyunexpressedcartilagecells.Severaltreatments,includingexposuretodibutyrylcyclicAMP,ascorbicacidandanatmosphereof5%oxygen,ormixturewithsmallnumbersofstage24wingmesenchymecells,stimulateexpression,asdeterminedbytheaccumulationofanAlcianblue-stainingmatrixandanultrastructurallyrecognizablecartilagematrix.Sincetheadditionofsimilarnumbersofdifferentiatedcartilagecellsdoesnotstimulateexpressionofstage26cells,itisproposedthatinitialcartilageexpressionisdependentonamesenchyme-specificinfluencewhichmightberemovedbycelldissociation.Thesestudiesdemonstratethatthereareatleasttwodistincttransitionsincartilagedifferentiation:oneinvolvestheconversionofmesenchymetounexpressedchondrocytesandthesecondinvolvesmesenchyme-dependentexpressionofchondrogenicdifferentiation.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
