Head involution in Drosophila: genetic and morphogenetic connections to dorsal closure

Dorsal closure and head involution are complex morphogenetic processes that occur nearly simultaneously, midway through Drosophila embryonic development. While dorsal closure has been studied extensively in terms of both its morphology and genetics, head involution has not been described comprehensively. A thorough review of the literature nonetheless reveals considerable information regarding the genetic components of head involution. In several instances, authors have made explicit references to head involution in regard to mutant phenotypes; in others, we have made this connection. Here we collect, catalogue, and discuss published head involution studies. In considering and integrating the data, an enhanced appreciation of the molecular mechanisms underlying head involution and its molecular kinship with dorsal closure has emerged.