During which phase, spermatogonium changes into primary spermatocyte?

Explanation

**Step-by-Step Solution:**

1. **Understanding Gametogenesis**: Gametogenesis is the process of forming gametes (sperm and eggs) in organisms. In males, this process is specifically called spermatogenesis.

2. **Identifying Spermatogonium**: Spermatogonium is the initial germ cell in the male reproductive system. It is diploid (2N), meaning it contains two sets of chromosomes.

3. **Mitosis Phase**: The first phase of spermatogenesis is known as the multiplication phase. During this phase, spermatogonia undergo mitotic division. This is also referred to as the multiplication phase because it involves the multiplication of spermatogonia.

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