Cholinergic amacrine cells express low levels of Pax6 and high levels of p27kip1 compared to other amacrine cells. Vertical sections of chick retina were labeled with antibodies to Pax6 (green; a, c, d and f) or p27kip1 (green; g, i, j and l) and ChAT (red). The tissues were obtained from chicks at E7 (a-c and g-i) and E11 (d-f and j-l). Arrows indicate cholinergic amacrine cells that are labeled for Pax6 or p27kip1, and small double arrows indicate p27kip1-negative cells in the progenitor cell layer of the E7 retina. The calibration bar (50 μm) in panel l applies to all panels. Abbreviations: ChAT – choline acetyltransferase; INL – inner nuclear layer; IPL – inner plexiform layer; GCL – ganglion cell layer.