Page 213 - Atlas of Histology with Functional Correlations

macrophages (phagocytes) during inflammation in the tissue. Blood

monocytes are precursors of the mononuclear phagocyte system. Although
the cytoplasm appears agranular and pale under a light microscope, the
cytoplasm is filled with small lysosomes. Once transformed into
macrophages and with their cytoplasm filled with hydrolytic enzymes of the
lysosomes, these cells destroy bacteria, cellular debris, and foreign matter.

Monocytes are also antigen-presenting cells and play an important role in
defense of the organism. They process antigens and present them to T
lymphocytes to induce an appropriate immune response.

Figure 6.10 | Human Blood Smear: Basophil,

Neutrophil, Erythrocytes, and Platelets

A high-magnification photomicrograph of a human blood smear shows
erythrocytes (3), a basophil (1), a neutrophil (5), and platelets (4). The
basophil (1) cytoplasm is filled with dense basophilic granules (2) that obscure
the nucleus. In contrast, the neutrophil (5) cytoplasm does not show granules,
and its nucleus is multilobed (6).

FIGURE 6.10 ■ Human blood smear: a basophil, a neutrophil, erythrocytes, and
platelets. Stain: Wright stain. ×320.

Figure 6.11 | Human Blood Smear: Monocyte,

Erythrocytes, and Platelets

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