Number of chromosomes in the primary oocyte is

Options

A. Same as that of secondary oocyte
B. Half as that of secondary oocyte
C. Double as that of secondary oocyte
D. Same as that of ovum

Answer

To determine the number of chromosomes in the primary oocyte, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Germinal Cells**: During fetal development, germinal cells in the human ovary differentiate and undergo mitotic division. These cells are known as oogonia.

2. **Oogonia Characteristics**: Oogonia are diploid cells, which means they contain two sets of chromosomes. This is denoted as 2n.

3. **Formation of Primary Oocyte**: The oogonia grow larger and then divide to produce primary oocytes. Since the primary oocyte is derived from the oogonia, it also remains diploid (2n).

4. **Meiosis Initiation**: The primary oocyte then begins the first meiotic division (meiosis I). This is a reductional division, meaning it reduces the chromosome number by half.

5. **Outcome of Meiosis I**: After meiosis I, the primary oocyte divides into two cells: one secondary oocyte and one polar body. The secondary oocyte is haploid (n), meaning it contains half the number of chromosomes compared to the primary oocyte.

6. **Conclusion**: Since the primary oocyte is diploid (2n) and the secondary oocyte is haploid (n), it follows that the number of chromosomes in the primary oocyte is double that of the secondary oocyte.

### Final Answer:
The number of chromosomes in the primary oocyte is **double that of the secondary oocyte**.

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