Decidua and implantation of the embryo from a historical perspective

Implantation of the embryo is critical for the initiation of intrauterine development of early embryos. It depends on the proper soil formed by the decidualized pregnant uterus. In the present article I have reviewed the evolution of the modern concepts of decidualization and embryonic implantation, emphasizing how closely interrelated these two processes are. Special emphasis and recognition is given to the Boston pathologist Arthur T. Hertig, who studied for 15 years with another Bostonian, John Rock, a gynecologist, human implantation and early embryogenesis, thus providing the basis for future studies of human reproductive biology, infertility and contraception.