The pathology of the human muscle spindle. A light microscopic, biometric and histochemical study.

Abstract

A biometric study was made on 810 muscle spindles in 214 muscles. The absence of atrophy of the intra-fusal muscle fibres and the frequency of spindles with focal dilatation of the periaxial space were the prominent features in denervated muscles. Thickening of the spindle capsule without atrophy of the intra-fusal muscle fibres was often seen in dystrophic muscles. The frequency of changes was greatest in cases of myositis. Eleven spindles were studied by histochemical techniques. In one case of denervation atrophy, all the intrafusal muscle fibres had an enzyme pattern similar to the grouping that occurs in extra-fusal fibres during reinnervation. The outer membranes of the thickened spindle capsule, frequent in dystrophic muscles, were 5-Nucleotidase rich an ATPase poor. The inner membrane was ATPase rich and 5-Nucleotidase poor.