The development of heterologous grafts, labeled with thymidine-3H in the cardiac area of the chick blastoderm☆

[摘要] Undercertainexperimentalconditions,E+Mofthenoncardiacarea(squares15–18ofFig.1)instages5−to5+,transplantedinthecardiacareaofanotherembryointhesamestage,wasincorporatedwithinthehostandhadthecapacityofdifferentiatingintohearttissue(endocardium,epimyocardium)andcoelomicmesotheliumofthehost(Figs.2–4).Theendodermofthesamesquaresgaverisetotheendodermoftheforegutandintestinalcanal.Duringthedevelopmenttherewasadisplacementbetweenthemesodermandendoderm,thefirstdisplacinginacranialdirectionwithrelationtothesecond.Thisdemonstratesthatintheseexperimentalcircumstancesgraftsofthesesquarestotheheartareacandifferentiateintostructuresdifferentfromthoseoftheirprospectivefateandthatthereforetheyarenotdeterminedoronlypartiallydeterminedatthetimeofgrafting.Inthesecases,theheterologousgraftcontinuedthemorphogeneticmovementsofthehostregionandbecameincorporatedwithinit,resultinginatypical,oralmosttypical,embryowithasingleheart,thesameasoccurswithahomologousgraft,e.g.,ofaheartarea.Inthecasesinwhichthegraftdidnotbecomeincorporatedwithintheembryo,theendodermofthegraftformedextraembryonicendodermofthehostbutcouldberecognized,even“intoto,”becauseofitsdifferentstructure(Figs.6and8).Eveninthesecases,isolatedcellscouldpassontothehostandformedpartsofsomeofitsstructures,butneverasacohesivesheetofcellsasinthecasesinwhichincorporationwascomplete.Evenwhenthegraftwasdividedintothreeorfourportions,asinthecaseofembryo2–68,thesefusedwiththemselvesandwiththehostanddevelopedasiftheywereonlyonepiece,goingontoformpartofthecoelomicmesotheliumandoftheendocardiumandmyoepicardiumoftheheartofthehost.

[学科分类] 生物科学（综合）