II.F.001

Monocyte, normal. Blood film. Three segmented neutrophils, two small lymphocytes. A monocyte is in the center of the field with a large, reniform nucleus and cytoplasmic color invariably distinctly different from that of neutrophils. The monocyte cytoplasm is blue-gray and the neutrophil is light tan. Note also the lighter staining, lacy nuclear appearance in the monocyte and the denser, condensed chromatin in the neutrophils.

II.F.002

Monocyte, normal. Blood film. A composite of four normal monocytes. (A) Folded nucleus. Modest amount of cytoplasm. (B) Folded nucleus. More ample, gray cytoplasm, cytoplasmic vacuoles (often secondary to exposure to Na₂EDTA anticoagulant. (C) Reniform nucleus. Ample cytoplasm, azure granules. (D) Circular nucleus. Azure granules.

II.F.003

Monocyte, normal. Blood film. (A) Monocyte with horseshoe-shaped nucleus with enlarged, folded end, gray cytoplasm. (B) Band neutrophil with horseshoe-shaped nucleus and pink-orange cytoplasm. The difference in cytoplasmic coloration is an invariable distinction between monocytes and band neutrophils by light microscopy.

II.F.004

Monocyte, normal. Blood film. Nucleus shaped like a reversed “E”. Ample gray cytoplasm. Small lymphocyte to the right.

II.F.005

Monocyte, normal. Blood film. Monocyte with horseshoe-shaped nucleus. Ample, gray cytoplasm, few azure granules.

II.F.006

Monocyte, normal. Blood film. Monocyte with reniform nucleus. Gray ample cytoplasm. Small lymphocyte to the left and segmented neutrophil below.

II.F.007

Monocyte, normal. Blood film. Monocyte with horseshoe-shaped nucleus with enlarged, folded end. Ample, gray cytoplasm. Small lymphocyte to the right.