The "tao" of integuments

Hair follicle and sweat gland fates can be switched by morphogens at specific skin regions or developmental stages The integument forms the interface between an organism and its environment. It serves diverse functions such as communication, endothermy, defense, and flight. During vertebrate evolution, various integumentary organs, including hairs, feathers, glands, and teeth, have evolved to help animals adapt to evolving environmental changes ( 1 ) (see the first figure). These ectodermal organs form through epithelial-dermal interactions. Classic tissue recombination experiments have demonstrated that the dermis specifies the organ phenotypes within a developmental time window ( 2 ). Yet the underlying mechanisms remain unclear. On page 1551 of this issue, Lu et al. ( 3 ) reveal the specific molecular mechanism whereby an epithelial placode can be guided to form either a hair follicle for its architecture or a sweat gland for its secretory function.