An accumulation of myofilamentous material within individual muscle fibers, forming usually round but occasionally elongated bodies ranging from 2 to 15 pm in size. The so-called spheroid bodies stain green with the modified trichrome preparation and are mainly present in the periphery of type 1 muscle fibers, where they may occupy large sectors sharply demarcated from the remainder of the cross-sectioned muscle fiber. [from
HPO]