Figure 7: RORβ1 promotes amacrine cell differentiation.

(a) Retinal sections of +/+ mice at P14 after electroporation at P0 with Ub/empty control or Ub/RORβ1-expression vector. Electroporated cells were identified by co-electroporated TdT marker. TdT⁺ (purple), calbindin⁺ or GABA⁺ amacrine cells (turquoise) and double-positive cells (white/whitish) were visualized by confocal imaging. Horizontal, amacrine and displaced amacrine cell zones are indicated by white, grey and black arrowheads, respectively. Ub/RORβ1 yielded many TdT⁺ amacrine cells with projections in the inner plexiform layer. Scale bar, 30 μm in all panels. (b) In RORβ1-deficient (1g/1g) pups electroporated at P0 and analysed at P14, Ub/RORβ1 yielded many TdT⁺ amacrine-like cells in the INL with projections in the inner plexiform layer. TdT⁺, calbindin⁺ cells with unusual projections in the outer plexiform layer may be mis-located amacrine cells in the disorganized INL of 1g/1g mice. (c) Counts of cells positive for amacrine (syntaxin, GABA, GlyT1) and combined amacrine/horizontal (calbindin) markers in +/+ (left) and 1g/1g (middle) mice. Counts represent marker⁺/TdT⁺ electroporated cells in 150 μm lengths of retina. Right, counts in +/+ mice of cells positive for TdT and bipolar (Chx10), Muller glial (glutamine synthetase, GS), rod (Nrl), cone (M and S opsin), ganglion (Brn3a) or horizontal (Lim1) cell markers. Means±s.d.; ≥6 eyes from ≥6 mice; *P<0.001. Statistical analyses were performed using Student’s t-test.