ENZYME LEVELS OF INDIVIDUAL NEURONS IN RELATION TO LIPOFUSCIN CONTENT

By quantitative histochemical methods, activities of (α-naphthyl) acid phosphatase and β-galactosidase, and of malate and lactate dehydrogenase, were measured in individual human anterior horn nerve cell bodies selected for high and low lipofuscin content. No significant differences were found. However, when single neurons were subdivided into pigmented and unpigmented portions, the two lysosomal enzymes were considerably more active, and malate and lactate dehydrogenase less active, in the lipofuscin-rich part of the cell. These results are consistent with the view that lipofuscin granules are derived from lysosomes.