Cytoplasmic vacuoles are often seen. The nucleus is irregular, frequently with delicate folds and often lobulated. The chromatin is fine and lacey, sometimes described as reticular. The mature monocyte has no nucleoli. Monocytes are phagocytes and frequently contain vacuoles.
Monocytes can migrate into tissues where they are known as macrophages.
Scanty light blue cytoplasm, while usually agranular, may contain a few small red granules. Contrast the chromatin of the lymphocyte and neutrophil. The lymphocyte at right is 15-18m dia. Lymphocytes with peripherially clumped chromatin and often deep blue cytplasm similar to plasma cells are termed plasmacytoid lymphocytes. The morphologic identification of a consecutive series of WBCs, by eye or automated instrument, results in a differential count, in which the relative number of each cell is expressed as a percentage.