Dense microspheres in the human hippocampus.

Dense microspheres (DMS) are structures found within neuronal processes of the adult human brain. Although best known as a feature of the neocortex, they are also found in the hippocampal formation. We describe a characteristic pattern of DMS distribution in the human hippocampus. The functional significance of this pattern is unknown, but it casts doubt on the proposed relationship of DMS to senile plaques. We also present evidence that DMS are composed of protein, but without a significant component of carbohydrate or neutral glycoprotein.