Fig. 7. Photomicrographs showing whole-mount preparations of the rat aorta (A,B) and the toad lateral aorta (C,D) following processing for NADPH diaphorase histochemistry (A,C) and endothelial nitric oxide synthase (NOS) immunohistochemistry (B,D). In the rat aorta, punctate NOS-positive staining (arrowheads) occurred around the nuclei (arrows) of the endothelial cells, which was demonstrable with both techniques (A,B). In contrast, no NOS-positive staining was observed around the nuclei of the endothelial cells in the toad lateral aorta (C,D). Scale bars, 10µm.