Myofibrillogenesis in vitro as seen with the scanning electron microscope

The present study describes an experimental approach whereby myofibrillogenesis and the three-dimensional arrangement of myofibrils present within cultured skeletal muscle cells can be examined using the scanning electron microscope. This procedure uses cells that have been cultured on gold-coated coverslips, and treated with Triton X-100 to extract the cell membrane and the soluble cytoplasm. Subsequent electroconductive staining by treatment with thiocarbohydrazide and osmium allows the myofibrils to be visualized. The images of myofibrils in various states of development observed by this method generally accords to those previously reported by transmission electron microscopy. Cell elongation and adhesion to the substrate causes mechanical stress from different directions which meet at branchings of the cultured myotubes. Many myofibrils are observed to run in the direction of the inferred stress lines.