Cleavage was first seen by

Options

A. Spallanzani
B. Aristotle
C. Hertwig
D. Harvey.

Answer

**Step-by-Step Solution:**

1. **Understanding Cleavage**: Cleavage refers to the process of cell division that occurs in the early stages of embryonic development. It involves the division of a single-celled zygote into multiple cells, leading to the formation of a multicellular embryo.

2. **Historical Context**: The question asks about the first scientist to observe cleavage. It is essential to look at the historical contributions to the study of embryology.

3. **Identifying Key Scientists**: The video mentions several scientists:
- Spallanzani
- Aristotle
- Hartwig
- Harvey

4. **Researching Contributions**:
- Spallanzani is credited with significant contributions to the study of reproduction and embryology.
- Aristotle, while an early biologist, did not specifically observe cleavage.
- Hartwig and Harvey also contributed to the field, but their work was not the first observation of cleavage.

5. **Conclusion**: Based on the information provided, Spallanzani was the first to observe cleavage in eggs in 1738.

6. **Final Answer**: Therefore, the correct answer is **A. Spallanzani**.

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