Correlative light optical, scanning electron, and transmission electron microscopy of skeletal muscle in muscular dystrophy and muscular atrophy: a pilot study.

Biopsies of skeletal muscle from three different cases of muscular dystrophy and one case of spinal muscular atrophy that has been fixed with Karnovsky's fluid were either routinely prepared for scanning electron microscopy (SEM) or were frozen to -20 degrees C and sectioned on a steel knife in a cryostat at 5-10 micrometer. The sections were coverslipped and examined using a light microscope equipped with polarizing optics (Pol). After areas were selected, the sections were prepared for SEM and thereby examined. The tissues on the slides that had been observed with light microscopy (LM) and SEM were prepared further for transmission electron microscopy (TEM) by infiltrating them with Epon and cutting sections at approximately 100 nm on an ultramicrotome. It is shown that the stage of contraction in one pathologic myofiber may vary along its length. The following advantages may be realized by using correlative (Pol leads to SEM leads to TEM) microscopy on skeletal muscle biopsies: 1) lesions can be differentiated from "normal" surrounding tissue; 2) doubtful structures can be reexamined with the SEM and TEM; and 3) the SEM image of different states of muscle contraction can be reinterpreted in the light of the Pol or TEM image.