Electron microscopic study on a case of idiocy: Astrocytes and mental deficiency

A biopsy of a frontal gyrus from a case of idiocy, without gross bodily symptoms or neurological signs, was examined by electron microscopy. The results of this examination were as follows: there was no destructive process in the cerebral tissue but inclusions were seen in the cytoplasm of the astrocytes and there was an abnormal increase in lipofuscin granules, in the cytoplasm of the nerve cells. The inclusions consisted of damaged endoplasmic reticulum and RNP granules. From these findings, it was considered that the physiological function of the astrocytes was disturbed, as the result of a disturbance in protein metabolism and that the function of the nerve cells was also disturbed, with an increase in lipofuscin granules. These changes seem to be intimately concerned with mental deficiency and part of intellectual function seems to depend on the functions of the glia cells.