Why is cleavage called a fractionating process?

Explanation

**Step-by-Step Solution:**

1. **Definition of Cleavage**: Cleavage is the process of cell division that occurs in the early stages of embryonic development. It starts after fertilization when the zygote begins to divide.

2. **Characteristics of Cleavage**: During cleavage, the zygote undergoes multiple rounds of mitotic division. This results in an increase in the number of cells, known as blastomeres, without a corresponding increase in the overall size of the embryo.

3. **Cell Size During Cleavage**: Although the number of cells increases, the size of each individual cell (blastomere) remains relatively constant. Initially, the zygote is a single large cell, but as it divides, the resulting cells are smaller in size compared to the original zygote.

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