Histochemical changes in the mesencephalic nucleus and motor nucleus following neurotomy of the third division of the trigeminal nerve.

Following unilateral section of the trigeminal third division, the ipsilateral mesencephalic neurons showed severe shrinkage with central chromatolysis and nuclear eccentricity while the motor neurons showed mild swelling. Histochemical reactions in the mesencephalic neurons were mostly characterized by the decreased activity of phosphorylase after 16hrs and concomitant diminution of PAS-positive substances. The increased activities of G6PDH and ACP were recognized in almost all neurons of both nuclei and in adjacent neuroglial cells. The neuropil in the motor nucleus showed remarkable decrease of SDH, ALD and LDH activities after 10 days. The results obtained were discussed in relation to chromatolysis, protein synthesis and carbohydrate metabolism in the affected neurons and surrounding neuropil.