The wall of the artery (1) is much thicker and contains more smooth muscle fibers than the wall of the vein (4). The innermost layer tunica intima of the artery (1) is stained dark because of the thick internal elastic lamina (1a). The thick middle layer of the muscular artery, the tunica media (1b), contains several layers of smooth muscle fibers, arranged in a circular pattern, and thin dark strands of elastic fibers (1b). On the periphery of the tunica media (1b) is the less conspicuous external elastic lamina (1c). Surrounding the artery is the connective tissue tunica adventitia (1d), which contains both the light-staining collagen fibers (2) and the dark-staining elastic fibers (3). The wall of the vein (4) also contains the layers tunica intima (4a), tunica media (4b), and tunica adventitia (4c). However, these three layers in the vein (4) are not as thick as those in the wall of the artery (1). Surrounding both vessels are capillary (5), arteriole (7), venule (6), and cells of the adipose tissue (8). Present in the lumina of both vessels (1, 4) are numerous erythrocytes and leukocytes
The wall of the artery (1) is much thicker and contains more smooth muscle fibers than the wall of the vein (4). The innermost layer tunica intima of the artery (1) is stained dark because of the thick internal elastic lamina (1a). The thick middle layer of the muscular artery, the tunica media (1b), contains several layers of smooth muscle fibers, arranged in a circular pattern, and thin dark strands of elastic fibers (1b). On the periphery of the tunica media (1b) is the less conspicuous external elastic lamina (1c). Surrounding the artery is the connective tissue tunica adventitia (1d), which contains both the light-staining collagen fibers (2) and the dark-staining elastic fibers (3). The wall of the vein (4) also contains the layers tunica intima (4a), tunica media (4b), and tunica adventitia (4c). However, these three layers in the vein (4) are not as thick as those in the wall of the artery (1). Surrounding both vessels are capillary (5), arteriole (7), venule (6), and cells of the adipose tissue (8). Present in the lumina of both vessels (1, 4) are numerous erythrocytes and leukocytes
Source: diFIORE’S ATLAS OF HISTOLOGY WITH FUNCTIONAL CORRELATIONS (ELEVENTH EDITION)