Histogenesis of fetal mouse isocortex and hippocampus in reaggregating cell cultures

[摘要] Hippocampusandisocortexfrombrainsoffetalmiceofgestationalage16daystonewborn(19–20dayspostconception)weredissociatedwithtrypsintoproducesuspensionsofsinglecells.Thesewereallowedtoaggregateinliquidmediuminrotatingculturesat36.5°Cfor6–8days.Thehistogeneticpatternsformedintheaggregateswerecharacteristicofthebrainregionsampledanddependedcloselyonthedevelopmentalstageofthetissueatthetimeofdissociation.Forhippocampus,cellsdissociatedatgestationalagesof16–18daysproducedlargeaggregateswithsegregationofhippocampalpyramidalcellsfromothercellpopulations,butwithoutfurtherorganization.Cellsdissociatedataverynarrowtimerangeabout18.5daysgestationproducedinaggregatesaremarkablehistogeneticpatterncloselyresemblingnormalhippocampalarchitecture,withacharacteristiccurvedpyramidalcelllayerofappropriatethicknessboundedaboveandbelowbycell-sparsezones,andinisolatedcasesadentategyrusandsubiculumintheirnormalrelationstothepyramidallayer.Thehistogeneticeventsincludedparallelalignmentofelongatehippocampalpyramidalcellsanduniformorientationoftheirapicalprocesses.Cellsfromfetusesolderthan18.5daysmixedrandomlyintheaggregates,apparentlyhavinglostthecapacityforself-organization.Thustheorientingmechanismisshowntobeoperativeonlyataveryspecifictimeinthedevelopmentalhistoryofthehippocampus.Thehistogeneticeventsoccurringinaggregatesofcellsfromdifferentdevelopmentalstagescorrelatedcloselywiththestateofhistogeneticdevelopmentintheintactundissociatedhippocampus.Asimilaranalysiswasperformedwithdissociatedandaggregatedcerebralisocorticalcells.Cellsdissociatedatgestationalagesbetween17.5and18.5daysformedsphericalaggregatescontaininganoutermostcell-sparse“molecularlayer”andadeeper,sharplydelimited,concentricallyarrangedcorticalplatecomposedofyoungneuronswithapicaldendritesdisposedradiallytowardtheoutersurfaceoftheaggregate.Cellsdissociatedfromyoungerfetusesattainedlittleorganizationin7daysinvitro,andcellsfromolderfetusesformedonlypooraggregateswithrandomlymixedcells.

[学科分类] 生物科学（综合）