title: Effects of restriction of fetal jaw movement on prenatal development of the temporalis muscle.
abstract: Jaw movement affects masticatory muscles during the postnatal period. Prenatal jaw movement has also been implicated in the development of the temporomandibular joint; however, its effect on prenatal development of the masticatory muscles has not been extensively analysed. In the present study, we examined the effects of the restriction of fetal jaw movement on the temporalis muscle, a major masticatory muscle, in mice by suturing the maxilla and mandible (sutured group) using an exo utero development system. We compared the morphology of the temporalis muscle between sutured, sham-operated and normal in utero groups. At embryonic day (E) 18.5, the volume of muscle fibres, but not that of connective tissue, in the temporalis muscle was decreased in the sutured group. The E18.5 temporalis muscle in the sutured group appeared morphologically similar to that of the E17.5 in utero group, except for frequent muscle fibre irregularities. By transmission electron microscopy, in the sutured group, the myofibrils were immature and scattered, the nuclei appeared comparatively immature, the mitochondria were expanded in volume with fewer cristae, and cytoplasmic inclusion bodies were frequently observed. Expression of Myf-6, a late myogenic transcription factor, by real-time RT-PCR was not significantly different between the sutured and sham-operated groups. These findings demonstrated approximately 1-day delay in the morphological development of the temporalis muscle in the sutured group, and some abnormalities were observed, although Myf-6 level was not affected in the sutured group. The present study revealed that the prenatal jaw movement influences the development of the temporalis muscle.
authors: Department of Developmental Biology, Shimane University, Enya-cho, Izumoshi, Japan.
authors: Esrat
authors: E
authors: Jahan
authors: Akihiro
authors: A
authors: Matsumoto
authors: Jun
authors: J
authors: Udagawa
authors: Ashiq Mahmood
authors: AM
authors: Rafiq
authors: Ryuju
authors: R
authors: Hashimoto
authors: Omar Ibna Faizur
authors: OI
authors: Rahman
authors: Hasina
authors: H
authors: Habib
authors: Joji
authors: J
authors: Sekine
authors: Hiroki
authors: H
authors: Otani
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D005260:Female; D047109:Fetal Development; D007568:Jaw / Q000196:embryology*; D051379:Mice; D008854:Microscopy, Electron; D009068:Movement; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013314:Stress, Mechanical; D013703:Temporal Muscle / Q000196:embryology*; D013704:Temporomandibular Joint / Q000196:embryology*
chemical_list: D012333:RNA, Messenger