Reduction in the latent period of the response to thyroxin by tadpole tail discs fused to discs pretreated with thyroxin☆

[摘要] Ithasbeenpreviouslyshownthattissueblockspreparedfromthetailfinsoftadpoles(Ranapipiens)surviveinvitroforseveralweeksandrespondtothyroxinbyshrinkageafteralatentperiodoffourormoredays(20°C).Ithasbeenpostulatedthatthisshrinkagecorrespondstothatofnormaltailtissueduringmetamorphicclimax.Thelonglatentperiodofthyroidactionispresumedtodependuponthetimerequiredtoformthenecessarycellularorbiochemicalintermediates.Ifsuchintermediatesareactivatedbythyroxinintheamphibiantailtissue,itmaybepossibletoshortenthelatentperiodofthethyroxinresponseoffintissuebyfusinguntreatedblockstoblockspreviouslytreatedwiththyroxin.Experimentsarereportedhereinwhichtailfinblocksobtainedfromtadpolespreviouslyimmersedinthyroxinfor3daysweredockedtorecipientblocksnotexposedtothishormone.Suchrecipienttissuesrespondedwithcharacteristicresorptiveactivitywithin24hr,insteadoftheminimumof4daysrequiredbycontroltissuesexposeddirectlytothyroxin.Itisinferredthatsomecomponentotherthanthyroxinwhichisactiveininducingresorptionistransmittedfromthetreatedtotheuntreatedblock.Presumably,thisisaproductnormallypresentlateinthelatentperiodofthyroxinaction.

[学科分类] 生物科学（综合）