The processes involved in animal embryonic development that counteract any abnormalities that may arise in the different developmental stages. Regulative (or regulation) embryos or eggs can compensate for the removal of sections of the embryo or egg at an early stage of development so that subsequent development is not affected; in such embryos the direction of development of the cells is not determined until cleavage is well advanced. Regulation also includes twinning: the formation of two embryos from the cleavage of a single embryo (see twins).