The site and sequence of action of 6-aminonicotinamide in causing bone malformations of embryonic chick limb and its relationship to normal development☆

[摘要] Theresultsreportedhereincludethefollowingfindings:(1)6-aminonicotinamide(6AN)affectscartilage-producingcells,resultinginsubsequentbonemalformations.(2)6ANcauseschondrogeniccellstodegenerate,aprocessmorphologicallysimilartothatpreviouslydescribedfortheactionof6ANonchicklimbmesodermalcellsinvitro.(3)6ANactsontheprocessofphenotypicexpressionorthenewlydeterminedchondrocyteasopposedtoactingonmaturechondrocytes.Degenerativeeffectsinthelimbarenotobserveduntilstage25correspondingtothefirstappearanceofstainablecartilaginousmatrixmaterial.Also,6ANactsonolderembryostoproducezonesofdegenerationofcartilageinvolvingaprocess,again,morphologicallysimilartothatdescribedfortheactionof6ANonchicklimbmesodermalcellsinvitro,andagainthisprocessdoesnotseemtoaffectmaturechondrocytes.(4)6ANiseffectiveforarelativelyshortperiod,about36hrafteritsintroductionintotheegg,asshownbytheinabilityofnicotinamidetocompletelycounteract6AN-causedeffects.Theseobservationsandothersareusedtodiscussthemodeofactionofnicotinamide-sensitiveteratogensaswellastheroleofnicotinamideininfluencingtheexpressionoflimbmesodermalcellsintomyogenicandchondrogenicphenotypes.

[学科分类] 生物科学（综合）