Figure 1.

The vertebrate retina has a laminar organization. (A) Sagittal section of a mature zebrafish retina in vivo, showing lamination of cell bodies. The retinal cells are labeled with a combination of membrane-tagged fluorescent proteins that allows the identification of all the major neuronal types. In Cyan, the photoreceptors and bipolar cells under Crx promoter (Crx:gapCFP). In yellow, the horizontal cells, amacrine cells, and displaced amacrine cells under Ptf1a promoter (Ptf1a:Gal4/UAS:gapYFP). In magenta, the retinal ganglion cells under Ath5 promoter (Atoh7:gapRFP). Arrows indicate horizontal cells and displaced-amacrine cells. This image is a courtesy of Jaroslav Icha. The dashed box shows the area depicted by the schematic representation in (B). (B) Schematic representation of a cross-section of the mature retina in zebrafish showing lamination of cell bodies and their neurites. The cell bodies of the retinal cell types are organized into three layers from apical to basal; the outer nuclear layer (ONL), the inner nuclear layer (INL), and the ganglion cell layer (GCL). These three layers are segregated by two plexiform layers enriched with axonal and dendritic processes, namely the outer plexiform layer (OPL) and the inner plexiform layer (IPL). The primary sensory neurons; rod and cone photoreceptors (cyan) are located at the most apical layer (ONL). The interneurons; horizontal cells (yellow), bipolar cells (blue), and amacrine cells (light yellow) are distributed along the apico-basal axis of the INL. The displaced amacrine cells (light yellow) and the output neurons retinal ganglion cells (magenta) occupy the most basal layer (GCL). PR, Photoreceptors; HC, horizontal cells; BC, bipolar cells; AC, amacrine cells; dAC, displaced amacrine cells; RGC, retinal ganglion cells.