Ultrastructural evidence of contractile systems in mouse palates prior to rotation☆☆☆

[摘要] Previousstudieshaveshownthatthepalatalshelvesofmouseembryossynthesizethecontractileproteinsactinandmyosinatarateequaltothatoftonguejustpriortoshelfmovement(day14.5).Thepurposeofthisstudywastoexaminethemorphologyofthepalatalshelvesforevidenceofacontractilesystem.MyosinATPasehistochemistrywasperformedonfrozensectionsofday-14.5fetalmouseheads.Threeareasofthepalatalshelvesgaveapositivereaction:1)Areactionproducttypicalofskeletalmuscleontheoralsideoftheposteriorpalate(region1);2)a“heavy-diffuse”reactionproductonthetonguesideextendingfromthetopmid-palatetotheposteriorend(region2);and3)a“light-diffuse”reactionproductalongtheoralepitheliuminthemid-palate(region3).Electronmicroscopyofexcisedday-14.5palateswascarriedoutafterfixationinglutaraldehydeoranacrolein-dichromatesolution.Region1containedalargeareaofdevelopingandadultlikeskeletalmuscle.Intheareaofregion2alargepopulationoffilamentous-richmesenchymalcellswasobserved.Inaddition,largeneuronscoursingthroughbothcontractilesystemswerenoted.Preliminaryobservationsinregion3indicatedthepossibilityofaprimitive(nonmuscle)contractilesysteminthatarea.Thecontractileandnervoussystemsinthepalate,priortorotation,indicatethepossibilitythataninnervatedembryonicmusclesystemmayprovidethe“intrinsicshelfforce”torotatetheshelves.

[学科分类] 生物科学（综合）