In 1 micron-thick serial cryosections, cathepsins B and D were found to coexist in both type A (macrophage-like) and type B (fibroblast-like) cells: the whole cytoplasm of the type A cells showed strong immunoreactivity, while the type B cells contained a few granular reaction products. It is therefore suggested that type A cells have a marked ability for intracellular digestion of organic materials.