Source of Support: None, Conflict of Interest: None
The primary requirement for the attachment of embryo to the uterine epithelium is the critical synchrony between the maternal tissue and the freely floating blastocryst. This in turn prepares the endometrium to become receptive and the blastocysts to attain eexpanded statei. The driving force of this phenomenon is the titre of the endogenous hormones, mainly the estrogen and progesterone. In principle the process of implantation begins in two phases, the apposition and the adhesion. While the former reflects on progressive intimacy between trophoblasts and luminal epithelial cells around the entire blastocyst, the latter begins on the antimesometrial side of the uterus in most of the rodent species. The exact biochemical or molecular basis of peri and immediate post-implantation changes that occur in embryonic cells, mainly the trophoblasts and the uterine endometrial cells are not know, and since to study such changes at cellular level is not possible in situ the in vitro studies offer the only alternative. To concentrate on this new methods have been adopted for detailed studies of the participating embryonic and maternal cells ex vivo with a view to identify the cells types isolated from the respective tissues following implantation. These cells maintained in complimented culture medium have been studied for morphological changes through optical transmission and scanning electron microscopes. In addition the macromolecules synthesized or secreted by these cells, while in incubation have been analysed in order to pinpoint the cell and stage specific markers.