Cover legend: Retinal Müller glia respond to depletion of internal calcium stores with a calcium wave. A clockwise sequence of images, acquired at 6–15 s intervals, depicts an intact Müller cell, a Müller cell body fragment and a photoreceptor cell body loaded with the ratiometric Ca²⁺ indicator dye Fura-2. Low intracellular calcium concentrations [Ca²⁺]i are shown as blue, whereas increases in [Ca²⁺]i are depicted in warmer hues (red = high). The top (12 o'clock) panel shows cells with stores depleted in Ca²⁺ -free saline. Activation of store-operated TRPC1 and Orai channels, induced by addition of 2 mM Ca²⁺ saline, initially elevates [Ca²⁺]i in the apical and endfoot processes of the radial glial cell from where Ca²⁺ propagates towards the cell body in the form of a slow transcellular wave, reaching peak [Ca²⁺]i at 51 s (6 o'clock). For more information, see the article by Molnár, Yarishkin et al. (pages 3184–3198).