Morphometric ultrastructural evaluation of the axonal endings in the neuromuscular junctions of pigeons after long lasting limitation of movement.

Ultrastructural quantitative and qualitative evaluations of axonal endings in the neuromuscular junctions of latissimus dorsi posterior muscle in the birds kept under limited mobility are performed. The investigation showed that as the time of hypodynamia is prolonged the degenerative changes appear in most of the axonal endings. In the earlier period of limited mobility the number and volume of internal structures of the axonal endings (mitochondria and synaptic vesicles) decreased. In the longer period of hypodynamia fragmentation of axonal endings and their resorption by the Schwann cell were observed. These changes are considered as the third, final period of degeneration of the investigated structures.