HISTOLOGY REVIEW Human Blood Dr Tim Ballard Department

HISTOLOGY REVIEW Human Blood Dr. Tim Ballard Department of Biology and Marine Biology

Blood film -- human – Wright – 40 x objective erythrocytes (10 μ diameter) thrombocytes (2 μ diameter) leukocytes (20 -30 μ diameter) A blood film is a smear of whole blood. Done properly, the cells lie in a sheet of single cells.

Blood film -- human – Wright – 40 x objective neutrophil Neutrophils (~60%) are named for their lack of characteristic cytoplasmic staining, but are readily identified by their multilobed nucleus (hence their name polymorphonuclear leukocytes or polymorphs or PMNs). Their nucleus typically contains 2 – 4 lobes. The cytoplasm contains three kinds of granules, all of which are related to the cell’s function as a phagocyte.

Blood film -- human – Wright – 40 x objective neutrophils

Blood film -- human – Wright – 40 x objective eosinophil Eosinophils (2 -4%) are about the same size as neutrophils. Their nuclei are typically bilobed. The cytoplasm contains two specific types of granules, the contents of which are responsible for the intense acidophilia (red stain) seen with Wright’s stain. The granule contents include histaminases (anti-histamines) and materials that have a strong cytotoxic effect on parasites.

Blood film -- human – Wright – 40 x objective neutrophil eosinophil

Blood film -- human – Wright – 40 x objective basophil Basophils (<1%) are about the same size of neutrophils (maybe a little smaller) and are so named because of the numerous large granules in the cytoplasm that stain purple (basophilia) with the basic dyes of Wright’s stain. The granules contain heparin and histamine, mediators of the inflammatory response. Basophils are related to mast cells located in the tissues.

Blood film -- human – Wright – 40 x objective eosinophil basophil

Blood film -- human – Wright – 40 x objective monocyte Monocytes (3 -8%) are the largest of the WBCs. They leave the general circulation in 1. 5 – 2 days to become wandering macrophages in the tissues and osteoclasts in the bone. The nucleus of the monocyte is typically flattened or indented. The cells are classified as agranulocytes because their granules are small and hard to visualize. The granules are lysosomes in keeping with the function of the cells as macrophages.

Blood film -- human – Wright – 40 x objective monocyte neutrophils

Blood film -- human – Wright – 40 x objective lymphocyte Lymphocytes (~30%) are the smallest of the WBCs. They come as small, medium, and large, the smallest of which are about the size of the RBCs. The nucleus is intensely staining, slightly indented, and mostly spherical. There is a thin rim of bluish-gray cytoplasm. They function in either cell-mediated or antibody-mediated immunity.

Blood film -- human – Wright – 40 x objective lymphocyte This is a large lymphocyte, not a macrophage. To call it a macrophage, the cell should be larger and have a flattened or indented nucleus.

Blood film -- human – Wright – 40 x objective lymphocyte neutrophil

Blood film -- human – Wright – 40 x objective monocyte lymphocyte end