This section from the dermis of thr skin shows an arteriole cut in cross section.
Two endothelial cell nuclei are cut in cross
section and bulge into the lumen of the vessel. A single smooth
muscle cell nucleus is wrapped around the outside of the endothelial
lining, indicating that the tunica media consists of only a single layer of
smooth muscle. The entire arteriole is surrounded by a layer of collagenous
connective tissue (tunica adventitia).
