A note on the distribution of glial cells in the molecular layer of the dentate gyrus.

The distribution of the perikarya of astrocytes and other glial cells in the molecular layer of the dentate gyrus has been studied in gold chloride-sublimate preparations of rats and of normal and reeler mice, and in plastic embedded material from young adult rats. Contrary to previous reports (Rose et al. [7]), we have found no evidence for a distinct "line" or "band" of astrocyte cell bodies along the interface between the zones of termination of the entorhinal and hippocampal afferents to the dentate gyrus. Indeed, apart from a conspicuous accumulation of astrocytes immediately beneath the pial surface and hippocampal fissure, the distribution of glial cells across the extent of the molecular layer appears to be more or less random. In view of this it is difficult to ascribe a critical role to the astrocytes in either determining the normal distribution of afferent fibers to the dentate gyrus or in promoting their re-organization following its partial deafferentation.