Junctional complexes in fetal rat small intestine during morphogenesis☆
[摘要] Duringthe7dayspriortobirth(Days15–22),thesmall-intestinalepitheliumofthefetalratchangesfromprimitivestratifiedtosimplecolumnarepitheliumwhichlinesvilliat19days.Asseeninthinsections,thisremodelinginvolvesrapidformationofnewjunctionalcomplexesandsecondarylumensbetweenepithelialcellsdeepinthestratifiedepithelium.Wehaveexaminedtheformationandreorganizationofjunctionalcomplexesinproximalsmallintestineof15-to19-dayfetalratsusingfreeze-fracturetechniques.OnDays15and16theepithelialcellssurroundingtheprimarylumenarejoinedbyconventionalapicaljunctionalcomplexes.Additionally,macularjunctionalcomplexesarelocatedondeeperepithelialcells.Thesedisplaynopolarityandconsistoftight-junctionstrandsintermixedwithgapjunction-likearraysanddesmosomes.OnDays17and18nonluminal,macularjunctionalcomplexesenlargeandsecondarylumensdevelopwithintheircenters.Asthesecondarylumensexpand,microvilliappearandthejunctionalcomplexpolarizesaboutthesecondarylumen;tight-junctionstrandsbecomeparalleltotheluminalsurface,desmosomesmigratebasolaterally,andgapjunction-likearraysdisappear.ByDay19,secondarylumenshavefusedwiththeprimarylumen;concomitantlossofapicalcellsresultsinformationofvillilinedbysimplecolumnarepitheliumwithpolarizedapicaltightjunctions.Theobservedpatternofjunctionalcomplexformationmayplayaroleinmaintainingbarrierfunctionandestablishingepithelialcellpolarityastheepitheliumisremodeled.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
