Botulinum Toxin Paralysis of Adult Monkey Extraocular Muscle: Structural Alterations in Orbital, Singly Innervated Muscle Fibers

摘要: • Botulinum toxin was injected into the medial rectus muscles of adult rhesus monkeys, with postinjection survival periods three to 56 days. Light and electron microscopic changes were most apparent in orbital, singly innervated muscle fibers, which, during acute stage (seven 28 days), exhibited denervationlike hypertrophy dispersion central mitochondria toward periphery fibers. Withdrawal capillary network on which this fiber type normally is dependent for oxidative function a secondary adaptive response disuse resulting from botulinum paralysis neuromuscular transmission. Neuromuscular junctions still present all types, although evidence sprouting apparent. In long term (following return at 42 fibers appeared normal vasculature recovered proportion decreased cross-sectional area