
Venule
The composition of the walls of veins is the most variable of all vessels, and the three tunics are not always well demarcated. The smallest venules, resembling large-diameter capillaries, are composed of endothelial cells and pericytes, which are multipotential cells with contractile properties. As venules enlarge, they acquire smooth muscle in the tunica media. 400x

Venules
The composition of the walls of veins is the most variable of all vessels, and the three tunics are not always well demarcated. The smallest venules, resembling large-diameter capillaries, are composed of endothelial cells and pericytes, which are multipotential cells with contractile properties. As venules enlarge, they acquire smooth muscle in the tunica media. 400x

- Endothelium
The composition of the walls of veins is the most variable of all vessels, and the three tunics are not always well demarcated. The smallest venules, resembling large-diameter capillaries, are composed of endothelial cells and pericytes, which are multipotential cells with contractile properties. As venules enlarge, they acquire smooth muscle in the tunica media. 400x

Loose connective tissue
The composition of the walls of veins is the most variable of all vessels, and the three tunics are not always well demarcated. The smallest venules, resembling large-diameter capillaries, are composed of endothelial cells and pericytes, which are multipotential cells with contractile properties. As venules enlarge, they acquire smooth muscle in the tunica media. 400x