Small artery - plastic section (40x
objective lens)
This plastic section from the colon shows an artery, cut in cross section.
The numerous endothelial cell nuclei that are
arrayed the lumen are cut in cross section, because the endothelial cells
are oriented parallel to the long axis of the vessel. Most of these nuclei
bulge into the lumen of the vessel. The simple squamous epithelium is covered
by 4-5 layers of smooth muscle (tunica
media). The smooth muscle cell nuclei
are cut in longitudinal section because the long axis of the smooth muscle
cells is perpendicular to the long axis of the vessel. Between the endothelium
and the smooth muscle cells is a broad, wavy line. This is the internal
elastic lamina, the innermost layer of the tunica media. The artery
is surrounded by a layer of collagenous connective tissue
(tunica adventitia), in which flattened fibroblast
nuclei can be seen wrapping around the outside of the vessel..
