Temporal expression of L-Maf and RaxL in developing chicken retina are arranged into mosaic pattern

Members of the maf gene family encode basic/leucine zipper transcription factors and play important roles during cell differentiation in vertebrate and Drosophila development. To investigate the possible roles of chicken lens-specific Maf (L-Maf)/MafA in retinal development, we analyzed its expression in the developing chicken retina. We first determined that L-Maf is expressed in a subset of ganglion cells, amacrine cells and rod cells during retinal development. To characterize further the L-Maf expressing cells during photoreceptor development, we compared the expression patterns of L-Maf and RaxL, a marker of cone cells. We found the L-Maf proteins are detectable from E10 between RaxL positive cone cells in outer nuclear layer (ONL). Subsequently, the expression of L-Maf is restricted to the innermost nuclear cells in the ONL during rod differentiation. In contrast, RaxL positive cone cells are distributed in the outermost layer of ONL. Furthermore, tangential retinal sections showed that L-Maf positive rods and RaxL positive cones form a mosaic pattern during photoreceptor development.