Fig. 8. Chick-mouse chimeras (sacrificed at E14) that had been transplanted with aorta-derived clonal cell line A4, at passage 25. (A) Whole-mount fluorescence of the transplant site, showing a cluster of GFP⁺ donor cells. (B) Section through a large vessel showing donor cells integrated into a large vessel wall (arrowhead) stained for smooth -actin. (C) A cluster of donor cells outside a small vessel, with one cell (arrowhead) double expressing GFP and SMA (yellow in the merged image). Inset: GFP circulating cells inside a small vessel (arrowhead). (D) Donor cells accumulate in the dermis but not in the epidermis (arrowhead). Merged image: GFP (green), Hoechst (blue) and myosin heavy chains (red) of an adjacent muscle primordium containing no donor cells. (E) Section through the myocardium showing several donor cells (yellow) in the myocardium (arrowhead) and in the sub-epicardium. (F) Section through the intestine showing donor cells in the smooth muscle layer (arrowhead) stained for SMA. (G) Section through axial tissues showing donor cells in the cartilage adjacent to the perichondrium (arrowhead), in the perichondrium (asterisk) and in the blood vessel (arrow), but not in the intervening muscle fibers. (H) Section through a muscle primordium, showing donor cells (green) intermixed with myosin heavy chain-positive muscle fibers (red). Arrowhead indicates double-labeled fibers.