Intranuclear inclusions in Schwann cells of aged fowl ciliary ganglia.

Schwann cells in ciliary ganglia of fowls aged five to seven years were found to contain numerous intranuclear inclusions and pseudo-inclusions. Similar inclusions were usually absent from both neurons and non-neuronal cells, including connective tissue cells, and were rare in Schwann cells of chickens aged less than five years. Inclusions were of two different types: filamentous bundles and granulofibrillar bodies. Individual nuclei contained one to three inclusions. Pseudo-inclusions, i.e. cytoplasmic pockets invaginated into the nuclei, were found more rarely and accompanied one or both types of 'true' inclusions. The possible significance of these findings in relation to ageing phenomena is discussed. It is concluded that intranuclear inclusions appear to be a consequence of nuclear/cellular activation and may be regarded as aggregates of previously dispersed intranuclear proteins.