Unlike mammalian embryos, avian embryos are closed systems (
cleidoic egg) that offer the ability to solely observe embryonic responses to a teratogen as compared to combined maternal responses, fetal responses, and maternal to fetal transport as seen within eutherian embryos.
mutilata, as with other species of Gehyra, are
cleidoic (calcified) and do not need environmental water (Bustard 1968); thus, once they are laid, they develop with little or no gas exchange across the shell.