HUMAN TROPHOBLAST CULTURES - MODELS FOR IMPLANTATION AND PERIIMPLANTATION TOXICOLOGY

Implantation is the process that leads from blastocyst attachment to i ts embedding in the uterine wall. It is widely believed that failure o f implantation is a common cause of pregnancy loss. Toxic agents can i nterfere directly with the process of implantation and therefore may a ccount for unexplained implantation failures. Our knowledge of human i mplantation remains limited, mainly due to the lack of adequate experi mental models. Studies of mechanisms underlying implantation in humans are by nature and for ethical reasons restricted to in vitro models. The aim of this review is to provide a critical evaluation of various in vitro models of implantation in humans, as well as essential backgr ound knowledge required for application of these models to the assessm ent of peri-implantation toxicity. Particular attention has been devot ed to cell-cell and cell-matrix interactions as possible endpoints in the screening of toxic agents.