Response of peritoneal cells to horseradish peroxidase and aldehyde-fixed erythrocytes in the mouse: an electron microscope study.

Abstract

In adult dd-mice, response of peritoneal free cells to either horseradish peroxidase (HRP) or glutaraldehyde-fixed erythrocytes were examined by electron microscopy. As reported previously (ABE et al., 1979), peritoneal free cells are classified into three types: type I, II and III cells. Type I cells are small lymphocytes, type II cells are medium-sized mononuclear cells, and type III cells are macrophages. The amount of HRP taken up is very large in type III cells. The cells contain numerous vacuoles filled with HRP. Type I and II cells also have vesicles containing HRP. The vesicles are fewer in type I cells than in type II. Type III cells rapidly enclose erythrocytes by thin cytoplasmic flaps and then ingest several erythrocytes. In type III cells, a labyrinth of ramifying tubes seen in the peripheral cytoplasm may serve as a reserve of the membrane system for allowing a rapid coverage and internalization of large foreign materials. A part of type II cells attach to erythrocytes and take them by a varying depth of invagination. Type I cells do not respond to erythrocytes at all. In conclusion, the three types of peritoneal cells can be differentiated by their response to foreign materials as well as by their cytologic features.