Ultrastructural changes in the anterior horn synapses of rat spinal cord under different locomotor conditions.

Ultrastructural changes in axodendritic synapses of the spinal cord ventral horn are studied in rats subjected to different locomotor conditions: immobilization, control and physical loading. Enhanced motor activity results in a reduction of the number of synaptic vesicles in the axon terminal, as well as flattening and diminution of their size. Other changes correlated with the different motor regimes are likewise established in the number of terminal ending's mitochondria, in "active zones", in subjunctional dense bodies, and in the bouton area. Data are treated by means of variation analysis. The significance of differences is established by "T"-criterion.