Current topic: transport mechanisms in preimplantation mammalian embryos

The main theme of this brief review article is that the study of membrane transport from a developmental point of view can be equated with the study of regulation. Although the blastocyst develops primarily under the control of the genetic information it inherits, it may also need maternal signals at critical stages. The study of blastocyst physiology is thus relevant to understanding the events leading up to implantation and to future research on the mechanisms of exchange between the mother and embryo during the initial stages of placentation. This information may be of considerable importance to understanding some of the causes of embryonic loss, which is particularly high around the time of implantation, and to understand some of the basic physiology of the embryo to fill gaps in our knowledge of in vitro fertilization processes. We feel that the mammalian blastocyst provides a unique model for the study of the development of vectorial transport systems in epithelia and, in the future, of patterns of genes that regulate this development.