The in vitro maintenance of the apical ectodermal ridge of the chick embryo wing bud: An assay for polarizing activity☆

[摘要] Wehavedevisedaninvitrobioassayforlimbbudpolarizingactivityinthechickembryo.Thisassayhasproventobearelativelyquickandeffectivetestforamorphogeneticfactorasymmetricallydistributedinthelimbbudwhichiscapableofmaintainingorthickeningtheapicalectodermalridge.Asmallsectionofthepreaxialborderofthechickembryowingbudwasculturedalone,withtissuefromtheposteriorborder,mid-dorsaloranteriorcornerofaseconddonorwing,orfromtheflank.Thetissuefromthepreaxialborder(respondingtissue)consistedofmesodermwithoverlyingectodermandapicalectodermalridge.Whentherespondingtissuewasculturedalone,withflank,orwithanteriorcornerlimbtissue,theapicalectodermalridgeflattenedin24–36hrandmanymacrophagesappearedintheunderlyingmesoderm.Whenculturedwithposteriorborderlimbtissuehowever,theapicalridgeoftherespondingtissueremainedthickenedforupto48hr.,andnomacrophagesappearintheunderlyingmesoderm.Thebehaviorofrespondingtissuewasintermediatebetweenthesetwoextremeswhenculturedwithmid-dorsallimbtissue.Themorphogeneticactivityassayedbythisprocedurethusseemstobepresentasagradientinthewingbud,withactivitydecreasingfromposteriortoanterior.Contactwiththerespondingtissueisnotrequiredtoenableposteriorbordertissuetoelicitridgethickeningandinhibitthecelldeath.

[学科分类] 生物科学（综合）