Cross-section of a human aorta showing the layers of its wall, light micrograph. The tunica media, rich in elastic sheets or lamellae, occupies most of the wall. In the lower part of the image, the tunica adventitia is placed, looser in appearance and devoid of elastic lamellae. Orcein stain for elastin. The image is, in reality, the negative of the microscopic image. In this way, the elastic elements, which now appear in bright green, stand out even more clearly. Magnification: x90 when printed at 10 centimetres across. |