Radial Artery

The walls of arteries and veins consist of three layers: the tunica interna (intima) 1 , the tunica me dia 2 and the tunica externa ( adventitia) 4 . There are two types of arteries: conducting and peripheral arteries. Conducting arterial walls contain many elastic f ibers and membranes: elastic arteries. Peripheral arteries show a special abundance of smooth muscle cells: muscular or distributing arteries. Muscular arteries show the layered character of the walls most impressively. The figure shows a cross-section of the peripheral radial artery. Figure b shows the tunica intima (top). It is separated from the tunica media 2 by the tunica elastic interna 3 , a membrane with the appearance of a corrugated sheet. The wide tunica me dia 2 (stained red in this figure) consists of a densely packed layer of spindle-shaped myocytes in a circular or helical arrangement. The dashed lines in the figure represent the nuclei of the muscle cells. The bottom layers in both figures show the tunica externa 4

1 Tunica intima

2 Tunica media

3 Internal elastic membrane

4 Tunica adventitia

Stain: a) alum hematoxylin-eosin; b) hemalum-orcein; magnification (both): × 120

References

Kuehnel, W.(2003). Color Atlas of Cytology, Histology, and Microscopic Anatomy. 4^th edition . Institute of Anatomy Universitätzu Luebeck Luebeck, Germany . Thieme Stuttgart · New York .