Ultrastructural studies on myofibrillogenesis and neogenesis of skeletal muscles after prolonged traction in rabbits.
Little is known about the morphological response of muscle after long term traction. The purpose of this study was to investigate the morphological changes of skeletal muscle during limb lengthening. After application of mini-extraskeletal fixator, the hindlimb of New Zealand white rabbit was osteotomized and then slowly lengthened at the rate of 1 mm/day up to a 20 mm gain in length. The muscles of hindlimbs were perfused and dissected. Morphological studies were performed at electron microscopic level. Transmission electron microscopy revealed foci of microtrauma at the myotendinous junction. The distance between the muscle fibers and tendon parenchyma increased, with numerous primitive mesenchyme-like cells interposed within this gap. The cytoplasmic space of these cells was devoid of myofibril formation at the ends of stretched fibers. Within the satellite near the myotendinous junction myofilament production was observed in various gradations of maturation. It is concluded that myofibrillogenesis with traction neogenesis of skeletal muscle during limb lengthening does exist and occurs mainly near the myotendinous junction. The myotendinous junction in mature skeletal muscle actively participated in the process of limb lengthening.
Sun
J S
JS
Department of Orthopedic Surgery, National Taiwan University Hospital, Taipei, R.O.C.
Hou
S M
SM
Hang
Y S
YS
Liu
T K
TK
Lu
K S
KS
D000818:Animals; D005260:Female; D008297:Male; D008854:Microscopy, Electron; D018485:Muscle Fibers, Skeletal / Q000502:physiology / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000502:physiology / Q000648:ultrastructure*; D011817:Rabbits; D012038:Regeneration / Q000502:physiology; D012149:Restraint, Physical; D012518:Sarcomeres / Q000648:ultrastructure