HISTOPATHOLOGICAL STUDY ON MOTOR END PLATE IN INVOLVED MUSCULAR TISSUE IN AMYOTROPHY

Abstract

1. Study was performed by silver impregnation method on nerve fibres and motor end plates in muscular tissue from autopsy 4 cases with neurogenic amyotrophy (3 cases of amyotrophic lateral sclerosis and 1 case of neuromyelitis optica) and 5 cases with myogenic amyotrophy (2 cases of progressive muscular dystrophy, 2 cases of myotonic dystrophy and 1 case myasthenia gravis). Control study was similarly made on skeletal muscular tissue from 1 biopsy and 4 autpsy cases.2. The control muscular tissue was rich in nerve fibre bundles, which longitudinally ran through muscular fibre bundles, branching and forming an end plate for each of the latter. The end plate consisted of the terminal arborization of subterminal axon, sole plate and end plate nuclei, with a caliber of 19.5μat minium, 52.7μat maxium and 32.1μon average. ATIR, i. e. ratio of the number of end plates to that subterminal axon was approximately 1. There was no finding of multiple innervation in the control cases.3. In muscular tissue involved in neurogenic amyotrophy, the common findings were decrease in nerve fibres among muscular fibres and diminution of end plates.And some of the observed terminal arborizations of the end plate were reduced in stainability. A case of amyotrophic lateral sclerosis of 10 year duration showed rich nerve fibre bundles in severely atrophied muscular tissue and collateral sprouting. Also end plates were observed in a large number, but their calibers were reduced.4. In 2 cases of progressive muscular dystrophy, nerve fibres were amply observed, but end plates were reduced in caliber, and simplified in structure. Also collateral sproutings and free endings were visible. These alterrations are considered to be secondary lesions, accompanying the degenerative atrophy of the muscle.5. Alterrations seen in myotonic dystrophy were nearly the same with those in progressive muscular dystrophy.6. In muscular tissue involved in myasthenia gravis, there were collateral sproutings from the subterminal axon and also multiple innervation. Many end plates showed complicatedly brahched structure, and slight elongation and segmentation were observed, though in a small number.7. Muscle spindles in muscular tissue were also examined. They showed no alterrations except in a case of myotonic dystrophy, in whom thickning of the capsule, edema in subcapsular space, reduction of intrafusal fibres in diameter and their increase in number were observed in some of the examined spindles. Thus the degenerative atrophy in this disease was sometimes accompanied by lesion in the muscle spindle.