anatomical structure formation involved in morphogenesis +
anatomical structure morphogenesis +
anatomical structure regression +
animal gross anatomical part developmental process
cellular developmental process +
dedifferentiation +
The process in which a specialized structure (cell, tissue or organ) loses structural or functional features that characterize it in the mature organism, or some other relatively stable phase of the organism's life history. Under certain conditions, these structures can revert back to the features of their ancestors.