Satellite cell of skeletal muscle fibers

A Mauro - The Journal of biophysical and biochemical cytology, 1961 - ncbi.nlm.nih.gov
A Mauro
The Journal of biophysical and biochemical cytology, 1961ncbi.nlm.nih.gov
In the course of an electron microscopic study of the peripheral region of the skeletal muscle
fiber of the frog, the presence of certain cells, intimately associated with the muscle fiber,
have been observed which we have chosen to call satellite cells. Since these cells have not
been reported previously and indeed might be of interest to students of muscle histology and
furthermore, as we shall suggest, might be pertinent to the vexing problem of skeletal muscle
regeneration, a brief communication describing this finding is warranted prior to a more …
In the course of an electron microscopic study of the peripheral region of the skeletal muscle fiber of the frog, the presence of certain cells, intimately associated with the muscle fiber, have been observed which we have chosen to call satellite cells. Since these cells have not been reported previously and indeed might be of interest to students of muscle histology and furthermore, as we shall suggest, might be pertinent to the vexing problem of skeletal muscle regeneration, a brief communication describing this finding is warranted prior to a more detailed study. The observations reported here have been made on bundles of fibers dissected from the tibialis anticus muscle of the frog. The material has been fixed by the conventional method with osmium tetroxide, and the embedding has been carried out with methacrylate and with epoxy (epon) resin. In sections that were" stained," the lead hydroxide solution of Watson (1) was used. As seen in the attached electron micrograph of the satellite cell, the striking paucity of cytoplasm relative to its nucleus results in the cell assuming the shape of the nucleus. In fact, it is virtually impossible to discern the cellular nature of this entity in the light microscope, as it appears to be indistinguishable from a peripheral muscle nucleus proper. In electron micrographs the cell is seen" wedged" between the plasma membrane of the muscle fiber and the basement membrane, which invests the fiber throughout its length in close association with the plasma membrane. The intimacy of this satellite cell with respect to the multinucleate muscle cell is further revealed in the fact that, in general, the surface of the muscle fiber is not distorted outward but instead the satellite cell protrudes inward pushing the myofibrils of the muscle cell aside. On the inner surface, the plasma membrane of the satellite cell is in appositon with the plasma membrane of the muscle cell.
Unfortunately, because of the limited observations and the difficulty in acquiring sufficient data readily with electron micrographic techniques, it is not possible at present to estimate the frequency of occurrence of these cells in a typical muscle fiber in our preparation of tibialis anticus muscle. The only generalization warranted at this time
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