A comparison of an ARTERY and VEIN showing the TUNICS (or Layers) cross section, 50X - Stockfoto

a comparison of an ARTERY and VEIN showing the TUNICS (or Layers), cross section, 50X. The artery wall is above and the vein is below. Immediately, one can see a much thicker artery wall, especially because the tunica media is thicker and has much more smooth muscle than the vein. Both show the Tunica interna (Intima) with endothelium, however, the internal elastic membrane (red) is much more prominent in the artery. The tunica externa (adventitia) is about the same thickness in both the artery and vein, but there are more elastic fibers in this coat in the artery. Both vessels show a lumen.