Question

What are the five basic types of leukocytes?

Answer 1

Leucocytes/White Blood Cells/W.B.C. - They are the most active and motile constituents. Total leukocyte count TLC of human blood is 5000-11000/mm³. They are devoid of hemoglobin and hence are colorless. They are nucleated and motile through amoeboid movement. They can squeeze through the capillary walls and reach the site of infection. They are produced in yellow bone marrow and spleen.

Based on their cytoplasm, nuclei, and staining properties, they are broadly divided as –

(I) Granulocytes

72% they are also of three types a) Neutrophils b) Basophils c) Acidophils

They are called granulocytes because of the presence of granules of different size in the cytoplasm.

(a) Neutrophils

1. Percentage – 60-70%
2. Staining property – can be stained by both acidic and basic dyes.
3. Shape of nucleus – 2-6 lobed nucleus is seen.
4. Size of cell – 10-12µ
5. Life span – 10-14 hours
6. Function – they are mainly phagocytic in action and shows maximum diapedesis. They
7. Other feature – it is the most abundant W.B.C in blood.

(b) Basophils

1. Percentage – 0.5-2%
2. Staining property – can be stained by basic dyes.
3. Shape of nucleus – “S” shaped nucleus.
4. Size of cell – 8-10µ
5. Life span – 10-14 hours
6. Function – it produce histamine and heparin.
7. Other feature – it is the smallest W.B.C. Granules are large. It transform into mast cells in connective tissues.

(c) Acidophils

1. Percentage – 2-4%
2. Staining property – can be stained by acidic dyes.
3. Shape of nucleus – bi lobed/spectacle shaped nucleus is seen.
4. Size of cell – 10-15µ
5. Life span – 10-14 hours
6. Function – they produce antihistamine which destroys toxic substance produced by antigen-antibody complexes. They increase in allergic conditions.
7. Other feature – their number is controlled by hormones produced by adrenal cortex. They have fine granules.

(II) Agranulocytes

28% they have clear cytoplasm i.e. without granules. They are of two types a) Monocytes b) Lymphocytes

(a) Monocytes

1. Percentage – 2-8%
2. Staining property – no granules no stain
3. Shape of nucleus – kidney shaped nucleus is seen.
4. Size of cell – 12-15µ (largest)
5. Life span – 10-14 hours
6. Function – they are mainly phagocytic in action. They transform to macrophages/histiocytes in tissue.
7. Other feature – increase during chronic infections.

(b) Lymphocytes

• Percentage – 25%
• Staining property – no granules no stain.
• Shape of nucleus – single large oval nucleus is seen.
• Size of cell – 8-12µ
• Life span – months to years
• Function – they are of two types T lymphocytes and B lymphocytes. They are produced in lymphoid tissues. They produce antibodies.
• Other feature – max life span