Differentiation occurred in what type of cells?

Meristematic cells in plants and embryonic stem cells in animals are the type of cells where differentiation occurs.

Explanation:

The process by which a cell becomes specialized in order to perform a specific function is called differentiating of cell. A cell that can differentiate into all cell types of the adult organism is known as pluripotent. Such cells are called meristematic cells in higher plants and embryonic stem cells in animals, though some groups report the presence of adult pluripotent cells.

I think it's skin cells that had differentiation