Ultrastructural changes in the muscle cells of denervated muscles of rat.

: The ultrastructural changes taking place in the diaphragm and plantaris of rat are followed up from the 3rd hour to 24th week after section of the peripheral nerve. The latter is either sectioned, or crushed. It is found out that the initial changes, consisting in an increase of the number of ribosomes and certain degree of mitochondrial destruction, are observed as early as the first 24 hours after denervation. The postdenervational changes are traced up to the occurrence of reinnervation with restoration of the myoneural junctions. A description is ade of the changes in the various organelles of the muscle cell, and of the appearance of spheromembranous bodies, hellical complex and destruction of the contractile apparatus. Differences in the course of the post-denervational process in the diaphragm and plantaris are outlined. The results obtained are discussed and comparatively studied with literature data.