Electron microscope observations on thick filaments isolated from striated muscle

Abstract

The size and appearance of thick filaments isolated in homogenates of rabbit skeletal muscle and the barnacle Balanus aquilia have been examined in the electron microscope. Specimens were prepared for microscopy by negative staining and by critical point drying followed by shadowing with platinum. The filaments from both types of muscle are about 180 A in diameter, but those from the barnacle muscle are several times as long as the filaments from rabbit skeletal muscle. Ultrastructure consisting of about 4–6 longitudinal strands has been observed in both types of filaments. In the specimens prepared by critical point drying, surface detail, attributed to the cross bridges or projections, has been observed, although in some instances the surfaces of the filaments appear to be smooth.