ABSTRACT
The decidua, although a transitory structure that develops during pregnancy in the endometrium of some animals, has a relevant role for the successful outcome of pregnancy and is a remarkable system for the study of cell biology phenomena such as cell differentiation and cell death. Decidua has been studied systematically since Krehbiel (1937) published his observations on the rat. There are still many unanswered questions regarding the functions of its cells and molecular products and their interaction with the embryo.
