Figure 1 of Martin, Mol Vis 2020; 26:731-741.

Figure 1. Murine and rat retinal flat mounts. Flat mounted retinas from mice or rats stained with lectin. The main vessels are arranged radially with alternating arteries and veins. A: Six arteries (a) are separated by three large and three smaller veins (v) in mice. The two largest veins form three peripheral arcs draining additionally the peripheral areas of the smaller veins without crossing an artery. Arteriovenous crossings are highly rare and are not found in most retinas. B: There are some arteriovenous crossings (indicated by green circles) in rats. Most crossings are found at two-thirds the distance between the optic nerve head and the periphery. Usually, the vein is crossing an artery to reach an area between two arterial branches or an area between two arteries with a small and short vein in between.