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Discuss the composition of Leukocytes

Discuss the composition of Leukocytes.

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Leucocytes are divided into two:

a. Granulocytes (containing granules in cytoplasm, e.g. neutrophils, basophils and eosinophils)

b. Agranulocytes (showing few granules in cytoplasm e.g. monocytes and lymphocytes)

Neutrophils form greatest number (60-70%) of all circulating white blood cells. The nucleus contains 2-3 lobes linked by fine threads of chromatin. The cells are found mainly in inner margins of capillaries and small vessels and they are important for defense against infection. They can migrate from blood vessels to tissues and engulf bacteria. Their numbers increase when there is acute infection.

Eosinophils are less than neutrophils (constituting 2-4% of circulating leucocytes in normal blood). They are about the same size as neutrophils and contain a characteristic bilobed nucleus. They have many granules that are stained by eosin. Their main function is to detoxify foreign protein introduced into the body via lungs or G.I.T., or toxins produced by bacteria and parasites.

Basophils make up less than 1% of blood leucocytes and are therefore difficult to find in normal blood smear. The nucleus is divided into irregular lobes and the granules in cytoplasm are blue-staining. They contain heparin (an anti-coagulant). The heparin is released in areas of inflammation so as to prevent clotting and stasis of blood and lymph.

Monocytes are the largest white blood cells. The nucleus is oval, horse-shoe or kidney-shaped and eccentrically placed. They are phagocytic cells.

Lymphocytes are divided into small lymphocytes and large lymphocytes. The small lymphocyte, which is predominant in blood, has a spherical nucleus, sometimes with an indentation. The cytoplasm is scanty
and appears as a thin rim around nucleus. The large lymphocyte also contains a spherical nucleus and a thin rim of cytoplasm around the nucleus. The main function of lymphocytes is formation of antibodies that circulate in the blood in response to antigens (foreign substances).

Platelets are also called thrombocytes. They are non-nucleated disc-like fragments of protoplasm found in blood. They promote blood clotting and help repair gaps in the walls of blood vessels, preventing loss of blood. In stained blood smears platelets often appear as clumps

marto answered the question on April 16, 2019 at 08:58

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Discuss the composition of Leukocytes

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