Figure 2
Scanning electron micrographs of the embryonic heart of Scyliorhinus canicula. Sagittal views of the heart at developmental stages 29 (a), 32 (b) and 33 (c, c′). The heart shows an ‘S’ shape. The sinus venosus (SV) and the atrium (A) occupy a dorsal position with regard to the ventricle (V) and the outflow tract, which consists of a conus arteriosus (C) and a bulbus arteriosus (B). In (a), the arrowheads point to intramyocardial cavities. In (b), the arrowheads mark the growing intramyocardial cavities. The arrow indicates the septum transversum. Note the presence of numerous perforations in the internal face of the ventricular wall. In (c), the ventricle shows conspicuous trabeculation. In (c′), perpendicular myocardial fascicles are anchored to the thin outer layer of myocardium (M). Ao, ventral aorta; L, liver; PC, pericardial cavity. Scale bars: 200 µm (a, b, c) and 30 µm (c′).
