[Ultrastructural changes in the connective tissue of skeletal muscles following denervation]

The ultrastructural changes found in the endomysium of rats after denervation of the diaphragm and m. plantaris were studied. Within the first week after crossing the peripheral nerve in the nedomysium there appeared an increased amount of neutrophils and monocytes as well as phagocytic material in the cytoplasm of histocytes. Activization of the cytoplasm of fibroblasts which manifested itself in the appearance of numerous vesicles and multiple free and bound ribosomes was detected by the end of the second and the beginning of the third weeks after denervation. At the same period eosinophils invaded the endomysium and became closely surrounded by numerous collagenic fibres. After reparation of neuromuscular synapses these changes disappeared. On the basis of these results and others founded in previous studies of denervated and reinnervated skeletal muscles the authors consider these changes in the endomysium appearing under the above experimental conditions to be manifestations of metabolic interrelations between the endomysium connective tissue and muscle fibres.