Figure 4.

Immunofluorescence staining of P0 NICD⁺ retinas. A–F, Nuclear GFP staining (green) indicates areas of NICD expression (NICD⁺). Note that scattered GFP⁺ cells are present in wild type areas of retina due to αPax6 expression in a subset of amacrine cells. A,C–F are P0 + 1 div. A, NICD⁺ areas (green) lack a distinct ganglion cell layer (GCL, arrowhead) and inner nuclear layer (INL, arrow). Ascl1⁺ progenitor cells (red) are present in NICD⁺ retinal areas, with a domain of expression expanded into the GCL and INL. B, NICD⁺ progenitors show normal expression of the mitotic marker PH3 (red). C, NICD⁺ progenitors express elevated levels of Sox2 (red). D, The early photoreceptor marker Otx2 (blue) is expressed in NICD⁺ areas, but the late photoreceptor marker recoverin (red) is not. E, Brn3⁺ ganglion cell precursors (red) and Tbr2⁺ amacrine cell precursors (blue) are present in NICD⁺ areas (arrow), but Brn3⁺/Tbr2⁺ mature ganglion cells are absent from the vitreal surface (arrowhead). F, Bright Pax6⁺ (red) and Bhlhb5⁺ (white) mature amacrine cells are absent from NICD⁺ areas. Scale bar: 100 μm. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]