The Chick Embryo Aortic Arch Assay

The chick aortic arch assay represents a major modification of the rat aortic ring assay. Originally developed for the specific purpose of testing thalidomide (which had previously been shown to have limited effects in rodents but strong effects in chick embryos), the assay avoids the use of laboratory animals, is rapid, with an assay time of 1–3days, and can be carried out in serum-free medium. Aortic arches are dissected from day 12–14 chick embryos and cut into rings similar to those of the rat aorta. When the rings are placed on Matrigel, substantial outgrowth of cells occurs within 48h, with the formation of vessel-like structures readily apparent. If the aortic arch is everted before explanting, the time for observing endothelial cell outgrowth can be reduced to 24h. Both growth-stimulating factors, such as VEGF-A or FGF-2, as well as inhibitory substances such as endostatin, can be added to the medium, where their effect becomes easily measured.