Through the Microscope: Blood Cells - Life's Blood

Basophil

Basophils are granulocytes that contain purple-blue granules that contain heparin and vasoactive compounds. They comprise approximately 0.5% of the total leukocyte count. Basophils participate in immediate hypersensitivity reactions, such as allergic reactions to wasp stings, and are also involved in some delayed hypersensitivity reactions. Basophils are the smallest circulating granulocytes, averaging 10 to 15 µm in diameter. The nucleus to cytoplasm ratio is about 1:1, and the nucleus is often unsegmented or bilobed, rarely with three or four lobes. The chromatin pattern is coarse and patchy, staining a deep blue to reddish-purple. The cytoplasm is a homogenous pale blue, but this is often obscured by the large dark granules.