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Abstract

A population of catecholamine-containing subependymal cells bordering the preoptic recess of the toad hypothalamus was studied by the rapid Golgi method to determine whether the cells have the characteristic contours of neurons or are instead secretory cells similar to peripheral chromaffin cells as proposed in an earlier study. Golgi impregnations of these cells reveal that they possess long basal processes which extend toward the lateral surface of the brain and which are covered with clusters of short projections and longer single projections. The relatively large caliber and rough surface of these processes distinguish them from axonal processes of neurons. Instead the cells closely resemble the ependymal cells bordering the preoptic recess with respect to the lateral course of the basal processes and with respect to the projections on these processes. The only qualitative difference between the ependymal and subependymal cells seen in Golgi preparations is the presence of apical processes projecting from the subependymal cell bodies through the ependymal layer to border on the ventricle. On the basis of this and the earlier study it is concluded that the subependymal cells do not have the characteristics of neurons but instead constitute a new cell type similar to ependymal cells but specialized for the synthesis, storage and secretion of catecholamines.