Steroid hormones strictly control the timing of sexual maturation and final body size both in vertebrates and invertebrates. In insects, the steroid hormone ecdysone controls the timing of the molts between larval instars as well as the transition

Cell-type specific transcriptional programs underlie the development and maintenance of organs. Not only distinct cell types within a tissue, even cells with supposedly identical cell fates show a high degree of transcriptional heterogeneity.