We describe our studies on the characterization of the cell phenotypes in the wall of the aortic-arch-derived arteries from "late" chicken embryos. Using immunocytochemistry with antibodies against smooth muscle cytoskeletal and basement membrane proteins, we show that the smooth muscle of the aortic-arch-derived arteries from 13- to 19-d-old embryos contains two cell phenotypes organized in interchanging lamellae. One cell phenotype (lamellar cells), but not the other cell phenotype (interlamellar cells), expresses the cytoskeletal proteins desmin and alpha smooth muscle actin (alpha SMactin). Both cell phenotypes express the cytoskeletal protein vimentin. Furthermore, the lamellar cells but not the interlamellar cells are surrounded by the basement membrane proteins laminin and collagen type IV. Performing quail-chick transplantation experiments and using a quail specific antibody, we show that both lamellar and interlamellar cells in the "aortic arches" of a 15-d-old chimeric embryo are derived from neural crest cells. We conclude that the aortic smooth muscle cells from "late" chicken embryos consist of two distinct cell phenotypes which are derived from a common lineage.