Figure 7.

Expression of α-SMA decreases with increasing vessel order in the retinal vasculature. A, A retinal region imaged in vivo (first panel) and as a whole-mount, labeled for the pericyte marker NG2, the contractile protein α-SMA, and with the vessel marker Isolectin-IB4. The three labels are merged in the last panel. Scale bar, 400 μm. B, Retinal vessels are labeled for NG2 and α-SMA with no enzymatic digestion (left panels) and with digestion with collagenase/dispase (right panels). Arrows indicate first-order vessels in which strong α-SMA labeling is observed after enzyme digestion. High branch order vessels often express low levels of α-SMA (arrowheads). Scale bars, 100 μm. C, The strength of α-SMA expression (low, medium, or high) is indicated for vessels of each order.