In what layer of the epiphyseal plate is the process of mitosis occurring?

The epiphyseal plate is where the elongation is in a long bone.

The epiphyseal plate is the area of elongation in a long bone. It includes a layer of hyaline cartilage where ossification can continue to occur in immature bones. We can divide the epiphyseal plate into a diaphyseal side (closer to the diaphysis) and an epiphyseal side (closer to the epiphysis).