Developing eggs of reptiles (including Aves) are sustained by “fetal membranes” — complex cellular structures that provide for the respiratory and nutritional needs of their embryos. We are using anatomical techniques to study development and cytology of the fetal membranes in various lizards and snakes. Resultant data offer insight into important aspects of egg function, as well as evolution of the amniote egg. Oviparous species under investigation include corn snakes (Pantherophis guttatus) from our own breeding colony, the North American fence lizard Sceloporus undulatus (in an ongoing collaboration with Dr. Tracy Langkilde) and two gekkonid genera (Chondrodactylus and Eublepharis, in a new collaboration with Dr. Robin Andrews).