[Role of duration and intensity of activation of afferent fibers in regulating morphologic shifts in a neuron].

The afferent impulsation has a regulating influence on morphological and histochemical shifts in the neuron. The size and staining of spinal motoneurons of the frog are changed depending on the force and duration of the applied high frequency stimulation of afferent fibres. The threshold 10-minute-long activation results in the increased size and lighter staining of nerve cells. An increased force of high frequency stimuli causes darker staining and a decreased size of the motoneurons under study. One-minute-long activation of the afferent fibres by electric stimuli of 50 imp/sec failed to cause changes in the size and staining of nerve cells. Prolongation of the activation till 10 minutes results in a sharp decrease of the neuron size. Further activation of the afferent fibres for 2 hours causes pathological shifts in the structure of motoneurons: their vacuolization and melting. Besides, there appears a great number of dark stretched intensively stained nerve cells.