Sarcoplasmic bodies in distal myopathy compared with nemaline rods.

Sarcoplasmic bodies in a late onset distal myopathy and rods in nemaline myopathy have been investigated by electron probe X-ray microanalysis correlated to light microscopy. Sarcoplasmic bodies were glassy, drop-shaped structures up to 10 microns of length and easily distinguished in the scanning mode of electron microscopy performed on thick freeze-dried cryosections. They were found to be source of X-ray spectra characterized by a high sulfur peak. On semithin epoxy sections the sarcoplasmic bodies were observed in the scanning transmission mode as electron-dense structures which, according to X-ray microanalysis, exhibited a high sulphur and osmium content, possibly indicating the presence of sulphydryl groups. The nemaline rods were of 3 different types as judged by their light-microscopical appearance. They were, however, not visible in the scanning mode of electron microscopy performed on freeze-dried unstained cryosections. There were small differences in the elemental composition between different rods within the same biopsy but these were not systematically related to the differences in morphological appearance.