Figure 1.

Diagrammatic representation of the series of interactions between the trophectoderm/trophoblast (TE) and luminal epithelium (LE) and subjacent stroma. Potential roles of cell adhesion molecules at each stage are indicated. 1) Pre-receptive polarised endometrial epithelium with desmosomes distributed along lateral LE cell surfaces and non-adhesive apical cell surface; 2) Receptive endometrium and initial embryo attachment: reorganisation of lateral LE adhesion complexes accompanies apical carbohydrate ligand engagement to tether blastocyst; integrins and cell–bound HB-EGF now become available for TE-binding; 3) Stabilisation of initial attachment by αv or other integrin-mediated adhesion involving bridging ligands shown; other components are also probably functional; 4) Potential signalling through cell adhesion ligand-receptor interaction including calmodulin and calcium.