Morpho-quantitative analysis of nuclear inclusions in periaqueductal grey matter neurons in the cat.

The morpho-quantitative analysis carried out in the neuronal population of the periaqueductal grey matter of the cat has shown that nuclear inclusions are mainly of the filamentous type and that they are distributed predominantly in the external region, i.e. in the part of the periaqueductal grey matter situated furthest from the cerebral aqueduct, where 30% of the cells contain nuclear inclusions. In the internal region, i.e. in the part nearest the subependymal zone, only 2% of the neurons have nuclear inclusions. The glia in the internal region is more abundant and surrounds each nerve cell body while in the external zone of the periaqueductal grey matter it is scanty and does not delimit the neuronal soma. This difference suggests that there may be a relationship between the incidence of nuclear inclusions and the neuron/glia ratio.