ULTRASTRUCTURAL STUDY OF MATURATION OF PERITONEAL MACROPHAGES IN HAMSTER

The ultrastructure of unstimulated and glycogen-stimulated peritoneal macrophages of the hamster is reported. Such morphological features as the frequent presence of nuclear bodies, the numerous focal dilatations of the perinuclear cisterna and of the rough endoplasmic reticulum containing granular material of moderate density, the abundance of microvesicles with electron-dense and electron-lucent cores, and, finally, the increase in large lysosomes are all associated with a process of maturation of these cells in the peritoneal cavity. The formation of large lysosomes results from the interaction of a great number of vacuolar and microvesicular structures. The sequence of these interactions cannot be followed adequately by acid phosphatase determination. The use of colloidal gold marker shows that lysosomes cannot be sharply differentiated into hetero- and autolysosomes, since they appear to be formed as a result of pinocytosis and phagocytosis as well as a result of mechanisms related to autophagy. © 1969 Academic Press, Inc.