Cytokines in implantation.

The process of implantation in the human involves 'invasion' of the maternal endometrium by the trophoblast surrounding the developing blastocyst, in response to which there is a cellular reaction in the endometrium. The overall situation has some features analogous to invasion by a tumour and some which are more characteristic of an inflammatory response. In addition, and also in common with cancer and inflammation, there is a release of biologically active molecules, including cytokines, at and around the implantation site. It is believed that these cytokines may play an important role in the successful establishment of the pregnancy; the evidence for this belief is examined in this review.