LYSOSOME FORMATION AND SURFACE CHANGES IN STIMULATED PERITONEAL CELLS

The cells of the peritoneum of the mouse have been studied with the electron microscope after stimulation in vitro and in vivo with glyceryl trioleate and glucan. Stimulation has two main morphological effects. There is an increase in the length of cytoplasmic processes, both finger-like and flap-like; this is apparent within an hour and lasts for several days. Several days after stimulation there is an increase in the number of lysosomes, accompanied by an increase, demonstrated cytochemically and biochemically, in acid phosphatase. The lysosomes fall into two groups, a group of small homogeneous bodies, the characteristic macrophage granules, and larger heterogeneous bodies. The small macrophage granules have a constant fine structural pattern. The morphological appearances suggest that they are in the main primary lysosomes, largely synthesized in the endoplasmic reticulum. The larger heterogeneous dense bodies probably contain varying amounts of ingested material, and can be considered as residual bodies. © 1968 Springer-Verlag.