Arthropod developmental endocrinology
Embryonic development in arthropods appears to be largely controlled by gene regulatory cascades and networks, and gene products that move by diffusion. By contrast, postembryonic growth and differentiation are controlled almost entirely by circulating hormones and secreted growth factors. Also, in contrast to the dozens and perhaps hundreds of genes that control early stages of embryonic specification and differentiation, only a very small handful of developmental hormones control an extraordinarily diverse array of postembryonic developmental processes ranging from growth, to moulting, metamorphosis, and the development of alternative phenotypes in response to environmental signals. Hormones such as ecdysone and juvenile hormone can have many categorically different effects, depending on the species, stage of the life cycle, and target tissue. Some hormones, such as ecdysone, appear to be used universally across the Arthropoda whereas others such as juvenile hormone and androgenic hormone are taxon restricted (to the Insecta and decapod Crustacea, respectively).
