Figure 6. Dscam lamination phenotypes.

Sections of retina from Dscam^FD/FD, Dscam^2J/2J mice and Dscam^F/F mice targeted with Pax6α Cre or Brn3b Cre were stained with antibodies to TH, OPN4, Syt2 and ChAT. A, DA cells normally laminate processes along the inner nuclear layer. mRGCs normally laminate adjacent to the inner nuclear layer and slightly offset proximal to the retinal ganglion cell layer. DA cells and mRGCs maintain normal lamination patterns in wild type and Dscam mutant retinas. B–K, Retinas from wild type, Dscam^FD/FD, Dscam^2J/2J and Dscam^F/F Pax6α Cre and Brn3b Cre mice were stained with antibodies to choline acetyl transferase (ChAT) to label cholinergic amacrine cells (B–K) and bNOS to label bNOS positive amacrine cells (B–F). B, bNOS labels three bands of neurites in the wild type inner plexiform layer. C and D, This pattern of lamination is lost in the Dscam^FD/FD and Dscam^2J/2J retina. E and F, bNOS lamination is maintained in the Dscam^F/F Brn3b Cre retina and in portions of the Dscam^F/F Pax6 Cre retina in which amacrine cells only are targeted, despite the presence of fasciculation (arrow). B and G, The neurites of cholinergic amacrine cells laminate in two bands in the wild type retina. C, D, H and I, Breaks in the lamination of cholinergic amacrine cell neurite bands are present in the Dscam^FD/FD and Dscam^2J/2J retina. E and J, Cholinergic amacrine neurite bands are disrupted in the Dscam^F/F Brn3b Cre retina, although not to the degree observed Dscam^FD or Dscam^2J mice. F and K, Cholinergic amacrine cell neurite bands laminate evenly in regions of the Dscam^F/F Pax6α Cre retina in which Cre is only expressed in amacrine cells. L and M, Whole wild type and Dscam^2J/2J retinas were stained with antibodies to ChAT to label cholinergic amacrine cells. The inner nuclear layer and OFF cholinergic band was imaged. Cholinergic amacrine cells arborize a diffuse net of processes in the wild type retina but this pattern is disrupted in the Dscam^2J/2J retina. The scale bar in (K) is equivalent to 105 μm in A–K and 52 μm in L and M.