Fig. 2. Chemokines stimulate cytotrophoblast migration. (A) Cytokeratin 7 (CK7) (red) and CXCL16 (green) expression in the region of the maternal-fetal interface shown in Fig. 1. (A) CXCL16-specific antibody stained invasive and endovascular cytotrophoblasts (CTBs), identified by their cytokeratin 7 expression. The nuclei of cells, which were stained with DAPI, appear blue. IVS, intervillous space; AV, anchoring villi. (B) Pertussis toxin (PTX) or a CXCR4-blocking antibody decreased cytotrophoblast migration required for aggregation in vitro. (C) In a migration assay, the addition of individual chemokines (CXCL12, CXCL16 and CCL21) stimulated cytotrophoblast migration in a dose-dependent manner, and the effects were additive. Error bars indicate s.d. (D) Checkerboard analysis in which the chemokines were added to either the upper, lower or both chambers revealed that these molecules stimulated cytotrophoblast migration by increasing chemokinesis. Scale bars: 100 µm.