The rat possesses hemochorial placentation with deep intrauterine trophoblast cell invasion
and trophoblast-directed uterine spiral artery remodeling; features shared with human
placentation. Recognition of these similarities spurred the establishment of in vitro and in
vivo research methods using the rat as an animal model to address mechanistic questions
regarding development of the hemochorial placenta. The purpose of this review is to provide
the requisite background to help move the rat to the forefront in placentation research.