Electron microscope study of the developing taste bud in rat fungiform papilla☆☆☆

[摘要] Anelectronmicroscopestudyofthemorphologicalsequenceofeventsoccurringinthedevelopmentofthefungiformpapillaandtastebudontherattonguehasbeenperformed.Forconvenienceofdescription,fivestagesofdevelopmenthavebeendefined:1.Stage1:Formationofepithelialeminencesassociatedwithconnectivetissuepapillaeonthedorsalsurfaceoftheembryonictongue.Connectivetissuecellsareseenincloseappositiontothebasementmembraneunderlyingtheepithelialeminences.Theseeminenceshaveadistributiononthefetaltonguesimilartothatoffungiformpapillaeontheadulttongue.2.Stage2:Growthofnervefibersintotheconnectivetissuecoreoftheformingfungiformpapilla.Small,densegranulesareseenintheproximalcytoplasmofthebasallayerofepithelialcellsatthetopofthefungiformpapilla.3.Stage3:Invasionofepitheliumatthetopofthefungiformpapillabynerveprocesses.Associatedwiththisistheappearanceofclustersofvesiclesintheepithelialcellsneartheirareaofcontactwithnerveprocesses.Thesevesicleshavebeeninterpretedasmorphologicalevidenceofaninteractionbetweenepithelialcellsandnerveprocesses,aninteractionwhichprecedesdifferentiationofthecellsintotastebudcells.4.Stage4:Differentiationofcellswhichassumetheconfigurationsarbitrarilydesignatedasperipheral,basal,andtypeIcells,thelatterpossessingapicalmicrovilli.Thedesignationofcelltypesisemployedforconveniencetodescribestagesofcellulardifferentiation.Thesurfaceofthefungiformpapillaiskeratinized.5.Stage5:TheappearanceoftypeIIcellsandthetastepore.ThetypeIIcellsarethoughttoplayanactiveroleintheformationandmaintenanceofthetastepore.

[学科分类] 生物科学（综合）