Fig. 2. Light micrograph of the origin of interarterial anastomoses (iaas) from a segmental artery. Anastomoses originate as depressions through the endothelial (E) and medial (M) layer of the primary vessel. Anastomoses follow a linear perpendicular path to the outer margin of the adventitial (A) layer, where they coil extensively (^*). Note the numerous microvilli (arrowheads). Scale bar, 10 µm. Lissamine Fast Red, 4 µm section.