Dense microspheres in normal human brain.

The normal postinfancy human brain contains microscopical structure referred to as the dense microsphere (DMS). The function and significance of the DMS are presently unknown. The light microscopical, topographical, histochemical and ultrastructural aspects of the DMS are described, based on the study of 106 normal and 50 diseased brains. The frequency of DMS in random samples of temporal neocortex was compared in 96 normals, 10 cases of Alzheimer's disease, 10 cases of Parkinson's disease, 10 cases of schizophrenia, and 20 cases of other nervous diseases. No significant differences were found between diagnostic categories but there was statistically significant reduction in frequency with ageing. These findings are discussed in relation to the possible significance of the DMS.