The effect of cortisone treatment and reoperation on reactive changes in the facial nucleus after axotomy

The material, with few exceptions, consists of PAS-gallocyanin stained paraffin sections from 4- to 6-month-old male rabbits fixed by perfusion first with saline and then with Bouin's solution. (1) In animals treated with cortisone prior to and subsequent to axotomy, the neurons exhibit an accelerated dispersal and delayed reconstitution of Nissl substance (ribosomes). While mitotic activity is depressed at various sites, formation of new microglial cells is evident. Neuronal degeneration with karyorrhexis is occasionally noted in single neurons in the lateral parts of the facial nucleus. An increase in intraneuronal glycogen deposition is manifested by a greater number of glycogen-rich neurons; such neurons are depleted of their glycogen after axotomy. (2) In other animals, reoperation of the facial nerve on the 6th, 22nd, 60th and 120th day, followed by survival of 3 days, results in dispersal of restored Nissl substance and in increased extravascular mitotic activity which is of less intensity than in single-operated animals.