Cytodifferentiation during insect metamorphosis: the galea of silkmoths.

In the galea of silkmoths undergoing metamorphosis, generalized epidermal cells, which had previousty secreted pupal cuticle, transform into highly specialized cells producing a new protein, the enzyme cocoonase. These cells first segregate by mitosis and displacement, then grow rapidly through endomitosis and accumulation of RNA-rich cytoplasm, and finally begin rapid synthesis of cocoonase. Replication of DNA continues in fully differentiated cells synthesizing cocoonase.