On fertilization of egg nucleus with sperm nucleus

Options

A. Second maturation is completed
B. Embryo is formed
C. First polar body is formed
D. First maturation is completed.

Answer

**Step-by-Step Solution:**

1. **Understanding Fertilization**: Fertilization is the process where the male gamete (sperm) fuses with the female gamete (egg) to form a zygote. This is a crucial step in sexual reproduction.

2. **Formation of the Zygote**: When the sperm nucleus and egg nucleus combine, they form a diploid cell known as a zygote. This zygote contains genetic material from both parents.

3. **Development Post-Fertilization**: After fertilization, the zygote undergoes several stages of development. The first stage is cleavage, where the zygote begins to divide and eventually forms an embryo.

4. **Analyzing the Options**:
- **Option A: Second maturation is completed** - This is incorrect as the second maturation refers to the completion of meiosis in the female gamete, which occurs before fertilization.
- **Option B: Embryo is formed** - This is correct as the zygote will develop into an embryo after fertilization.
- **Option C: First polar body is formed** - This is incorrect; the first polar body is formed during oogenesis before fertilization.
- **Option D: First maturation is completed** - This is also incorrect as it refers to the maturation of the oocyte, which occurs prior to fertilization.

5. **Conclusion**: Based on the analysis of the options, the most appropriate answer to the question is **Option B: embryo is formed**.