Crystalloid bodies in skeletal muscle of hypothyroid myopathy

Abstract

Crystalloid bodies in skeletal muscle fibers have been described in myopathic and non-myopathic conditions. They have been interpreted as viral, glycogen, protein-glycogen complex, artifacts and of unknown nature. This report described similar crystalloid bodies in the postmortem muscle samples of two patients with hypothyroid myopathy. The crystalloid bodies were preferentially located in the I band and Z line region and in the subsarcolemmal region closely associated with lipofuscin. Some were present within basophilic bodies. They were formed by parallel filaments of 6-10 nm beaded periodically by electron-dense particles of 10-18 nm in a lattice, hexagonal or parallel-ripple pattern. Merging of filaments of crystalloid bodies into actin filaments of the I band was noted. The electron-dense particles stained strongly with periodic acid-thiocarbohydrazide-silver proteinate method for polysaccharides and were unaffected or partially digested by diastase treatment on the ultrathin sections. The filamentous component was neither stained for polysaccharides nor digested by diastase treatment. It is suggested that crystalloid bodies of muscle fibers are composed of two distinct subunits with particles of glycogen complex attached to filaments of unknown nature.

Comparative structural analyses of purified glycogen particles from rat liver, human skeletal muscle and commercial preparations

“…This kind of mechanical memory is common in polymers, especially branched and tangled ones like glycogen [36]. Skeletal muscle hexagon structures have been reported previously, firstly as crystalline hexagon lattices in skeletal muscle from hypothyroid myopathy [37], and secondly in a study that noticed translocation of glycogen synthase to novel hexagon-like structures in skeletal muscle [38]. We propose that these structures might simply be concentrated areas of glycogen particles.…”

Phosphorylation-dependent Translocation of Glycogen Synthase to a Novel Structure during Glycogen Resynthesis

“…Nevertheless, previous ultrastructural and histochemical studies have shown that the crystalloid bodies have two distinct components with particles of glycogen attached to filaments of unknown nature. They are formed by parallel filaments of 6 -10 nm, beaded periodically by electron-dense particles of 10 -18 nm in a lattice, hexagonal, or parallel-ripple pattern (37). The contractile apparatus of skeletal muscle is composed of repeating units, i.e.…”

169th ENMC International Workshop Rare Structural Congenital Myopathies 6–8 November 2009, Naarden, The Netherlands

“…Biochemical assessment of glycogenolysis in muscle of two patients did not reveal any abnormality. This myopathy should be differentiated from a myopathy with tubulin-reactive crystalloid inclusions [15,16], and from nonspecific myopathic changes with crystalline aggregates of protein–glycogen complexes, also called virus-like particles [17,18]. We concluded that myopathy with hexagonally cross-linked crystalloid inclusions is associated with a homogeneous clinical and histopathological phenotype.…”