In the following stage oogonia stop their division and enter into prophase - I of meiotic division

Options

A. Primary oocyte
B. Secondary oocyte
C. Tertiary oocyte
D. Ootid

Answer

### Step-by-Step Solution:

1. **Understanding Oogenesis**: Oogenesis is the process of formation of ova (egg cells) in the female reproductive system. It begins with the formation of oogonia.

2. **Formation of Oogonia**: Oogonia are the initial germ cells that undergo mitosis to increase their number. This process occurs during the embryonic development of females.

3. **Transition to Primary Oocytes**: After a certain number of divisions, oogonia differentiate into primary oocytes. This transition marks the beginning of meiosis.

4. **Arrest in Prophase I**: The primary oocytes enter the first meiotic division but are arrested in prophase I. This means that they stop their division at this stage and remain in this state until puberty.

5. **Completion of Meiosis**: After puberty, the primary oocytes can resume meiosis, completing the first meiotic division to form secondary oocytes and polar bodies.

6. **Conclusion**: The question asks at which stage the oogonia stop their division and enter prophase I of meiotic division. The correct answer is **primary oocytes**, as they are the cells that are arrested in prophase I.

### Final Answer:
The stage at which oogonia stop their division and enter prophase I of meiotic division is **primary oocytes**.

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