Development of grafts from mouse embryos to the wing bud of the chick embryo☆

[摘要] Theapicalzoneofembryonicmouselimbbudswhentransplantedtothedorsalsurfaceof3-daychickwingbudsdevelopsintowell-formedtoes.Theseareaboutthesizeofnormalmousetoesofthesamechronologicalageandaresmallinproportionto10–15daychickhostwings.Chickcartilageandconnectivetissueareincludedintheproximalpartofthetoes.Mesodermfromyoungmouselimbbuds(equivalenttochickwingbudsofstages18–24)wheninsertedbetweentheectodermalridgeandapicalmesodermofchickwingbudsremainsintheapexoftheoutgrowingbud,growsrapidly,anddifferentiatesintocartilagesandotherconnectivetissuesassociatedwiththedigitalstructuresofthehostmanus.Thelocation,size,andnumberofelements,andoccasionaltoelikeoutgrowths,indicatethatthemouseimplantsdifferentiateastoes.Mesodermfromoldermouselimbsorfromthemaxillaryprocesswhensimilarlyimplantedinthechickwingbudinterfereswithdistalelongationofthehostbud.Mitoticactivityoccursintheimplant,buttheamountofgrowthismarkedlylessthanthatobservedwhenlimbbudmesodermisimplanted.Theseobservationsdemonstratethatgraftsfrommouseembryostothechickwingbuddevelopinthesamemannerascorrespondinggraftsfromvariousregionsofchickembryos,andexhibitthesamesharpdistinctionbetweenthebehavioroflimbbudmesodermandothermesoderm.Mouselimbbuddevelopmentthusrequiresthesameinteractionbetweentheectodermalapicalridgeandthelimbbudmesodermthatoccursinthechick.Theincreasedsizewhichresultsfromgrowthintheimplantedmousemesodermcanbeobserveddirectlyduringthelimbbudstages.Thefindingthatalargeincreaseoccurswithoutinterminglingofchickcellswiththemousecellsdemonstratesthatmigrationfromproximallevelsisnotanecessaryfactorindistalelongation.

[学科分类] 生物科学（综合）