The three-dimensional cytoarchitecture of developing murine muscle spindles☆
[摘要] Themorphogenesisofmusclespindlesinthemouseextensordigitorumlonguswasstudiedincloselyspaced,serial,ultrathintransversesections,permittingevaluationofthedevelopingspindles'three-dimensionalcytoarchitecture.Afferentnerveterminalsareidentifiableasearlyas15daysinutero,andtheadultnumberofspindlesispresentat17daysinutero.Byestablishingcontinuitybetweentheclearlyidentifiableequatorialregionsandthepolarregions,whicharemorphologicallyindistinguishablefromsurroundingextrafusalfibers,itcouldbedeterminedthatfusimotorinnervationwaspresentbythe19thdayoftheinuterodevelopment.Inallspindlesexamined,theefferentinnervationoccurredextracapsularly.Atbirth,theadultnumber(fourorfive)ofintrafusalfibersarefoundineachspindle,andfusimotorinnervationisfrequentlyintracapsular.Evidenceispresentedsupportingthehypothesisthatsuccessivegenerationsofintrafusalmyotubesareformedbythefusionofmononucleatedcells.Newlyformedmyotubesarepreferentiallydistributedincloserelationshiptothesensory-innervatedregionoftheprimaryintrafusalmyotube.Analysesofgrowthparametersindicatethatthedifferenceinlengthanddiameterbetweenintrafusalandextrafusalfibersisprincipallyapostnatalphenomenon.
[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]
