From the very beginning of anatomical investigation, animal models were extensively used for elucidating the structure and function of the various organs of the human body. A recurrent feature of hemochorial placentation is the transformation of the endometrium into decidua, which is thought to play a role in the regulation of trophoblast invasion. This chapter discusses possible vascular remodeling defects after experimental induction of preeclampsia-like conditions in laboratory animals. Little information is available about the exact time when vascular invasion starts in the human. Interstitial trophoblast is involved in spiral artery remodeling, although its actual impact is still under discussion. When in search for an animal model, it seems appropriate to focus on species with deep endovascular invasion, in which one may try to interfere with some of the steps in the vascular remodeling process.