Normal Leukocytes

Abstract

Under the SEM, it is frequently possible to distinguish monocytes from lymphocytes. Monocytes (Figs. 9–30) are larger, more irregular cells with prominent ruffled membranes and ridge-like profiles and microvilli are not a prominent feature (Figs. 9–19). These cells can phagocytose latex beads or erythrocytes when placed in contact with them, and this process can be well visualized under the SEM (Fig. 20). Furthermore, the monocytes in monocyte-EA rosettes, when studied by SEM, show similar surface features (Figs. 21, 22) and frequently phagocytose the attached erythrocytes. Like macrophages, monocytes attach to glass and spread, becoming flatter and more irregular, and develop broad, frequently undulating cytoplasmic veils which attach to the underlying substrate (Figs. 23–30). After 2–3 days, many cells become elongated, with thicker cord-like extensions of cytoplasm which attach onto the glass (Fig. 27).