Japanese Journal of Veterinary Research;Volume 34, Number 1

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ULTRASTRUCTURAL : STUDIES ON MUSCULAR ATROPHY IN MAREK'S DISEASE II. MUSCULAR LESIONS IN SPONTANEOUS CASES

MADARAME, Hiroo;FUJIMOTO, Yutaka;MORIGUCHI, Ryozo

Permalink : http://hdl.handle.net/2115/4643
JaLCDOI : 10.14943/jjvr.34.1.51
KEYWORDS : atrophic fibers;myofilaments;targetoid fibers;honeycomb-like structures

Abstract

The skeletal muscles of 14 spontaneous cases of MD were investigated by light and electron microscopy. The muscular lesions of MD were classified into 3 categories : Category I-myoatrophic changes, Category II-myodegenerative changes, and Category III-neoplastic proliferative changes. The present investigation was focused on the Category I lesions. Light microscopically, the atrophic fibers were sparsely distributed between the normal sized muscle fibers in mild cases. In the advanced stage, there were often clear-cut groups of atrophic fibers, and finally, groups of variable numbers of atrophic fibers were extensively seen. Electron microscopically, irregularity of the fiber outline was commonly seen. The process of myofibrillary breakdown was conspicuous and seemed to start with disruption of the regular alignment of the myofilaments and streaming of Z-bands. The intermyofibrillar spaces were enlarged. The central nuclei with irregular shapes were often arranged in a row and increased in number. Targetoid fibers, honeycomb-like structures, and satellite cell activity were also observed. These findings were similar to those seen in experimental denervation. Therefore, the authors attributed these atrophic changes to neurogenic origin.

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