The chick embryo chorioallantoic membrane as a model to investigate the angiogenic properties of human endometrium

The chick embryo chorioallantoic membrane (CAM) is an established in vivo a ngiogenesis assay. The aim of our study was to assess the angiogenic proper ties of endometrium and to quantitate the vascular response in an accurate way. Samples of proliferative endometrium (n = 17) and control mouse skin t issue (n = 8) were explanted onto the CAM at day 10 of incubation. Addition al controls consisted of normal unmanipulated CAM (n = 12). Four days after grafting, photographs of the explant and the surrounding area were taken i n ovo to measure the vascular density index (VDI). The VDI is a stereologic al estimate of vessel number and length, which was obtained by counting the intersections of vessels with a circular grid superimposed on a computeriz ed image. Endometrium caused a significant increase in VDI as compared to b oth unmanipulated CAM (p < 0.001) and skin tissue as a control (p < 0.007). The intra-observer variability was 5.2%. This study demonstrates that the CAM assay is a suitable model to assess the angiogenic properties of endome trium. Furthermore, it allows detailed quantitation of the vascular respons e in an objective and reproducible way. Our findings suggest the CAM to be a promising model to study the role of angiogenesis in both normal human en dometrium and diseases involving the endometrium.