(C and D) Hand-drawn diagrams of the cells in (A) and (B), respectively. Cells with the nuclear features of cones are highlighted in blue. Note that the number of such cells is greater in the mutant, and their cell bodies are scattered throughout the outer nuclear layer. In addition, the overall columnar architecture of the outer nuclear layer seen in the wild type is disrupted in this portion of the mutant retina. Other portions of the mutant retina with fewer supernumerary cone cells, however, retain the normal columnar appearance (unpublished data).