An array of nonendothelial cell types is present in vascularized collagen implants after incubation on the CAM.

Twenty-micron cryosections through bFGF/VEGF-treated collagen implants were stained using cell type–restricted antibodies (red) and counterstained for nuclei (green). (A) Anti–α-smooth muscle actin stains fibroblastic cells (myofibroblasts) that appear in the upper regions of the implant. Bar indicates 200 μm. Individual myofibroblast-like cells, oriented in parallel, are shown at higher magnification (inset; bar, 10 μm). A large blood vessel lumen (lu) is lined by α-smooth muscle actin-positive cells. (B) Antibody CVI-ChNL-68.1, a marker for chicken macrophages, identifies specific cells that are present throughout the vascularized implant (arrowheads). Bar indicates 200 μm. At higher magnification, these cells are tissue macrophage–like in appearance (inset; bar, 20 μm).