Retinas lacking MG show intraretinal tears or “retinoschisis” in the GCL. Confocal images of the living fish retina in vivo. The retina is double transgenic for both vsx1:GFP, labeling most bipolar cells (green), and ath5:gapRFP, strongly labeling retinal ganglion cells in the GCL (red). (A–D) At 72 hpf (A and B) and 96 hpf (C and D), DAPT-treated retinas lacking MG have a specific ripping in the GCL (dashed line) along the basal surface of the retina (white solid line). (E) The Su(H) morphant retina does not have MG, as shown by the loss of GFAP:GFP-positive cells. (F) We did not observe any ripping within the retina of control fish. However, ripping in the GCL occurs in similar proportions in Su(H) morphant and DAPT-treated retinas (n = 50 retinas for each condition). (G and H) Electron microscopy shows local ripping within the GCL along the basal-most portion of the retina (arrowheads). Bars, 20 µm.