Urodeles Remove Mesoderm from the Superficial Layer by Subduction through a Bilateral Primitive Streak

Developmental Biology

David R. Shook¹  Christina Majer¹  Ray Keller¹ 

[1] Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia, 22904-4328

关键词: endocytosis;    Keller sandwich explants;    giant sandwich explants;    ingression;    primitive streak;    subduction;    Ambystoma maculatum;    Ambystoma mexicanum;    Taricha granulosa;    superficial mesoderm;    epithelial–mesenchymal transition;    epithelial morphogenesis;   

DOI  :  10.1006/dbio.2002.0718

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Urodelesbegingastrulationwithmuchoftheirpresumptivemesoderminthesuperficialcelllayer,allofwhichmustmoveintothedeeplayersduringdevelopment.WestudiedthemorphogenesisofsuperficialmesodermintheurodelesAmbystomamaculatum,Ambystomamexicanum,andTarichagranulosa.Inallthreespecies,somitic,lateral,andventralmesodermmoveintothedeeplayerduringgastrulation,ingressingthrougha“bilateralprimitivestreak”justinsidetheblastopore.Themesodermalepitheliumappearstoslideundertheendodermalepitheliumbyamechanismweterm“subduction.”Subductionremovesthelargeexpanseofsuperficialpresumptivesomiticandlateral–ventralmesodermthatinitiallyseparatesthesub-blastoporalendodermfromthenotochord,leavingtheendodermboundingthestillepithelialnotochordalongthegastrocoelroof.Subductionmaybeacommonfeatureofurodelegastrulation,differinginthisregardfromanurans.Subductingcellsconstricttheirapicesandbecomebottle-shapedastheyapproachthejunctionofthemesodermalandendodermalepithelia.Subductingbottlecellsendocytoseapicalmembraneandwithdrawthetightjunctionalcomponentcingulinfromthecontractingcircumferentialtightjunctions.Eitherinconjunctionwithorimmediatelyaftersubducting,themesodermalcellsundergoanepithelial-to-mesenchymaltransition.Themechanismbywhichepithelialcellsreleasetheirapicaljunctionstobecomemesenchymal,withoutdisruptingtheintegrityoftheepithelium,remainsmysterious,butthissystemshouldproveusefulinunderstandingthisprocessinadevelopmentalcontext.

【 授权许可】

Unknown