Here's why:

* Mitosis is a process of cell division that produces two identical daughter cells from a single parent cell. This is essential for the growth and development of the embryo as it needs to rapidly increase the number of cells to form tissues and organs.

* Meiosis, on the other hand, is a process that produces gametes (sperm and egg cells) with half the number of chromosomes as the parent cell. Meiosis occurs in the reproductive organs and is not directly involved in embryonic development.

Therefore, mitosis is the primary mode of cell division in the embryo.