An evaluation of methods to quantitate the chick chorioallantoic membrane assay in angiogenesis

The vascular responses by chick chorioallantoic membranes (CAM) to more than 150 normal and chemically injured rat corneas grafted to shell-less chicken CAMs were evaluated independently by three observers in a masked fashion by in vivo stereomicroscopy, projections of colored transparencies, and by light microscopy of tissue sections of the grafts. The experience gained from this study is reviewed as a point of focus for the strengths and weaknesses of the CAM technique in the assay of potential angiogenic substances. Despite certain shortcomings, the CAM technique can provide useful information relevant to studies on angiogenesis, particularly when the subjective CAM method is supplemented by histological evaluation of grafted tissues.