Disassembly of the zonula occludens during amphibian neurulation☆

[摘要] Thin-sectionandfreeze-fractureexperimentsconductedonRanapipiensembryosrevealthatthezonulaoccludensdisassemblesinanorderlyfashionduringneurulation.Earlyfeaturesoftightjunctiondedifferentiationincludeanattenuationofjunctionalelementsandtheappearanceofintramembraneparticlesinthenormally,particle-free,furrowedaspectoftheEface.Quickly,thejunctionthenfragmentsintodomainsleadingtoabreakdowninthepermeabilitybarrier.Thesedomainsarecomposedofshort,fibrillarremnantsandparticulatearraysinP-faceprofile.E-Faceimagesdisclosefewerparticulatedfurrows.Ultimately,junctionalcomponentsassociatedwithbothfacesofthemembranedisappearleavingrandomlyscatteredgapjunctionsintheirwake.Althoughthemechanism(s)regulatingdisassemblyareunknown,changesintheinteractionsbetweentightjunctionsubunitsaresuspectedtobeinvolved.Aredistributionofintramembraneparticlesbetweentheapicalandlateralcellsurfacesofthedevelopingneuroepitheliumalsoaccompaniestightjunctiondisassembly.Theembryonicsurface,whichdisplaysauniformpopulationof120Ã…particles,istransformedintotheneuroepithelialsurfacecomprisedofaheterogeneousclass(80–120Ã…)ofparticlesthatisindistinguishablefromtheintramembraneparticlesinthelateralcellmembranes.Itisbelievedthatchangesinmembranepolarityoccurasthezonulaoccludensdisassembles.

[学科分类] 生物科学（综合）