Fig. 1. Sternal artery. (A) Arterial spread treated with Rhodamine–phalloidin. Staining of the cells in the middle layer (tunica intermedia) of the vessel is strong. Scale bar, 100 µm. (B) Horizontal electron micrograph of an artery where the inner layer (ti, tunica interna) interfaces with the tunica intermedia. Bundles of microfilaments (mf) appear in the cortical cytoplasm and account for the fluorescence of cells in the tunica intermedia. Individual microfilaments are 6.5 nm in diameter. Dense filamentous mats are applied to the inner and outer surfaces of the plasmalemmata. Scale bar, 1 µm.