Neurons of the claustrum in the cat; a Golgi study.

The insular claustrum of the cat was studied using Kopsch modification of the Golgi technique. Neurons with or without dendritic spines were found. Among spiny neurons large pyramid-like cells with one main dendrite (S I type) appeared most frequently. Spindle-shaped neurons with two main dendrites (S II type) and multipolar ones (S III type) occurred much less frequently. Two types of aspimny multipolar neurons were found-larger (A I type) and smaller (A II type). Both were observed only in the posterior areas of the claustrum, mainly in its visual part. In the narrower regions of the claustrum, especialy in its anterior and posterior part, the dendritic fields of neurons were mostly arranged parallel to the surface of the claustrum. Centrally in the broader intermediate part of the claustrum long axes of neurons were oriented in various directions.