Biochemical responses of the luminal epithelium and uterine sensitization

In our discussion of responses of the uterine epithelium to the blastocyst and their relationship to sensitization to deciduogenic stimuli, we have attempted to identify pieces of information that could be arranged into possible mechanisms. These choices and the limits of space resulted in a great deal of information that was not mentioned: changes in the charge and composition of the glycocalyx of the luminal epithelium, the morphology of the apical surface of the epithelium, steroid hormone receptor levels, epithelial protein synthesis, and most of the information obtained from species other than rats and mice. Despite whatever distortion that may have resulted from our reductions and simplifications of the mechanisms of implantation, it should be clear that blastocyst implantation involves communication not only between blastocyst and uterus, but also between various uterine tissues. Our understanding of implantation will be improved if we can identify the responses of individual tissues and the mechanisms of this communication. It seems likely that development and loss of uterine sensitivity controlled by progesterone and estradiol will depend upon separate biochemical responses in specific uterine tissues.