Barr body is absent in normal human female in

Options

A. Skin cells
B. Leucocytes
C. Oogonia
D. Secretory cells.

Answer

**Step-by-Step Solution:**

1. **Understanding Barr Body**: A Barr body is an inactivated X chromosome found in females. In normal human females, there are two X chromosomes (XX), but only one of them is active in each cell, while the other is inactivated and forms the Barr body.

2. **Identifying the Cell Types**: The question asks in which of the following cell types the Barr body is absent:
- Skin cells (somatic cells)
- Oogonia (germ cells)
- Secretory cells (somatic cells)

3. **Analyzing Skin Cells and Secretory Cells**: Both skin cells and secretory cells are somatic cells. In somatic cells of normal females, both X chromosomes are present, and therefore, one will be inactivated, resulting in the presence of a Barr body.

4. **Analyzing Oogonia**: Oogonia are the precursor cells to ova (egg cells) and are haploid, meaning they have only one set of chromosomes. Since they only have one X chromosome, there is no second X chromosome to inactivate, and thus, no Barr body is formed.

5. **Conclusion**: Since Barr bodies are formed from the inactivation of one of the two X chromosomes in somatic cells, and since oogonia only have one X chromosome, Barr bodies are absent in oogonia.

**Final Answer**: Barr body is absent in normal human females in **oogonia**.

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