Glycogen accumulation in synaptic boutons in Clarke's nucleus neuropil after sciatic nerve crush at birth. An electron microscopic study.

Glycogen accumulation in the Clarke's nucleus neuropil of young adult rats whose sciatic nerves were crushed in the first postnatal day was investigated with the electron microscope. Glycogen was observed in synaptic boutons and in small myelinated axons. In some terminals, glycogen accumulated in membrane-bound structures resembling mitochondria and formed large multigranular bodies which were entirely separated from the axoplasm. The multigranular body reached the size of 1.3 micron. Glycogen was present as single beta particles of about 25-40 nm in diameter and in aggregations of large alpha clusters. The astrocytic glycogen distribution was almost similar to that of the control specimens. Glycogen was not observed in other glial cells. It is probable that glycogen accumulation in synaptic terminals of partially deafferentiated Clarke's nucleus may result from impaired glycolysis due to deficient resupply of the distal axon with glycolytic enzymes caused by a defect in axoplasmic transport from the hypoplastic sensory neuronal perikarya.