title: Characteristics of myofibres in the masseter muscle of mice during postnatal growth period.
abstract: Functional maturation of muscles is related to the constitutional proportion of muscle protein isoforms during development and growth. Although the mouse masseter muscle (MS) is classified as a fast limb muscle, its functions are different from those of a limb muscle. This study investigated the differentiation of myosin heavy chain (MHC) isoforms during the postnatal development periods in mouse MS and mouse tibialis anterior (TA), which is a fast limb muscle. Many anti-MHC slow-type-positive fibres were observed in neonatal MS and TA; these fibres decreased during development. Adult MS was composed of anti-MHC fast-type-positive fibres. MHC isoforms in MS were composed of MHC-2a and MHC-2d soon after birth. MHC-2b was expressed, but MHC-2a was not seen after 21 days. Expression of MHC-2b agreed with the weaning period, that is 2-3 weeks after birth. This fact suggested that the transformation from suckling to mastication changed the MHC isoforms during this period. In this study, the expressions of MHC-2b agree with the weaning period.
authors.affiliation: Department of Anatomy and Oral Health Science Centre, Tokyo Dental College, Chiba City, Chiba, Japan. kgojo@tdc.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Gojo
authors.forename: S
authors.initials: S
authors.lastname: Abe
authors.forename: Y
authors.initials: Y
authors.lastname: Ide
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D007150:Immunohistochemistry / Q000662:veterinary; D007536:Isomerism; D008297:Male; D008406:Masseter Muscle / Q000033:anatomy & histology* / Q000502:physiology; D051379:Mice / Q000033:anatomy & histology* / Q000502:physiology; D008813:Mice, Inbred ICR; D018485:Muscle Fibers, Skeletal / Q000737:chemistry*; D018995:Myosin Heavy Chains / Q000032:analysis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary
chemical_list: D018995:Myosin Heavy Chains