Quantitative ultrastructural features of maturing mononuclear phagocytes in rat peritoneal fluids

Summary Ultrastructural features of the in vivo transformation of macrophage congeners in resident and adjuvant-induced peritoneal populations are evaluated by stereological methods. Maturation involves an increase in cell size by the differential hypertrophy of subcellular compartments, notably remaining cytoplasm, nucleus and lysosome-like granules. Larger cells have more and larger granules, more mitochondria and a greater plasmalemmal surface. In contrast, adjuvant activation tends to produce fewer granules and a nett loss of surface membrane.I wish to thank Professor R. Barer for his advice and helpful criticism. Thanks are also due to the Wellcome Trust for financial support.