Leucopaenia is the condition in which

Options

A. The total number of leucocytes decreases below 4500/cu mm
B. The total number of leucocytes increases above 6000/cu mm
C. Bone marrow is destroyed
D. Formation of leucoytes stops

Answer

**Step-by-Step Solution:**

1. **Understanding Blood Cells**: Blood is composed of three major types of cells: erythrocytes (RBCs), leukocytes (WBCs), and platelets.

2. **Identifying Leukocytes**: Leukocytes, or white blood cells, are crucial for the immune response and are categorized into two groups: granulocytes and agranulocytes. Granulocytes include neutrophils, basophils, and eosinophils, while agranulocytes include lymphocytes and monocytes.

3. **Normal Range of Leukocytes**: In a healthy individual, the normal count of leukocytes ranges from 6,000 to 8,000 per cubic millimeter of blood.

4. **Defining Leukopenia**: Leukopenia is a medical condition characterized by a decrease in the total number of leukocytes. Specifically, it occurs when the leukocyte count drops below 4,500 per cubic millimeter.

5. **Conclusion**: Therefore, leukopenia is defined as the condition in which the total number of leukocytes decreases below 4,500 per cubic millimeter.

**Final Answer**: Leucopaenia is the condition in which the total number of leukocytes decreases below 4,500 per cubic millimeter.

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