Note that the irregular lumen of the vein is wide and its wall relatively thin. There is no internal elastic lamella in the wall of this vein. The purplish layer underlying the endothelium contains some smooth muscle cells plus collagen and elastic fibres (blue arrows). The external layer of the vein contains acidophilic collagen and black elastic fibres.

(Framed area) In the loose connective tissue surrounding the vein there are two small vessels (V) shown at a higher magnification in Figure 5.27.

Stain: Verhoeff
Magnification: ×150