Intrafusal myosin heavy chain expression of human masseter and biceps muscles at young age shows fundamental similarities but also marked differences
2013 (English)In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 139, no 6, 895-907 p.Article in journal (Other academic) Published
Muscle spindles are skeletal muscle mechanoreceptors that provide proprioceptive information to the central nervous system. The human adult masseter muscle has greater number, larger and more complex muscle spindles than the adult biceps. For a better knowledge of muscle diversity and physiological properties, this study examined the myosin heavy chain (MyHC) expression of muscle spindle intrafusal fibres in the human young masseter and young biceps muscles by using a panel of monoclonal antibodies (mAbs) against different MyHC isoforms. Eight MyHC isoforms were detected in both muscles-slow-tonic, I, IIa, IIx, foetal, embryonic, α-cardiac and an isoform not previously reported in intrafusal fibres, termed IIx'. Individual fibres co-expressed 2-6 isoforms. MyHC-slow tonic separated bag(1), AS-bag(1) and bag(2) fibres from chain fibres. Typically, bag fibres also expressed MyHC-I and α-cardiac, whereas chain fibres expressed IIa and foetal. In the young masseter 98 % of bag(1) showed MyHC-α cardiac versus 30 % in the young biceps, 35 % of bag(2) showed MyHC-IIx' versus none in biceps, 17 % of the chain fibres showed MyHC-I versus 61 % in the biceps. In conclusion, the result showed fundamental similarities in intrafusal MyHC expression between young masseter and biceps, but also marked differences implying muscle-specific proprioceptive control, probably related to diverse evolutionary and developmental origins. Finding of similarities in MyHC expression between young and adult masseter and biceps muscle spindles, respectively, in accordance with previously reported similarities in mATPase fibre type composition suggest early maturation of muscle spindles, preceding extrafusal fibres in growth and maturation.
Place, publisher, year, edition, pages
Springer, 2013. Vol. 139, no 6, 895-907 p.
Jaw, Limb, Human, Muscle spindles, Intrafusal fibres, Myosin heavy chain, Immuno-histochemistry
IdentifiersURN: urn:nbn:se:umu:diva-46771DOI: 10.1007/s00418-012-1072-7ISI: 000319167800008PubMedID: 23306907OAI: oai:DiVA.org:umu-46771DiVA: diva2:440654