P2RX7 and retinal ischemia: In preliminary experiments with a small number of animals (n = 3–4), an increased microglia reaction (Figure 5A) and microglia number (Figure 5B) as well as other Iba1/P2X7-positive cells (possibly invading macrophages, Figure 5—figure supplement 1) were observed upon transient retinal ischemia in wt animals.