Cuticle itself as a central and dynamic player in shaping cuticle

The wide variety of external morphologies has underlain the evolutionary success of insects. The insect exoskeleton, or cuticle, which covers the entire body and constitutes the external morphology, is extracellular matrix produced by the epidermis. How is cuticle shaped during development? Past studies have mainly focused on patterning, differentiation and morphogenesis of the epidermis. Recently, however, it is becoming clear that cuticle itself plays important and active roles in regulation of cuticle shape. Studies in the past several years show that pre-existing cuticle can influence shaping of new cuticle, and cuticle can sculpt its own shape through its material property. In this review, I summarize recent advances and discuss future prospects.