Figure 2. Dopamine receptor deletion does not alter photoreceptor cell survival in rd1 retinal organ cultures. Retinas from D1^−/−, rd1/+ (A), D1^+/−, rd1/rd1 (B), D1^−/−, rd1/rd1 (C), D2^−/−, rd1/rd1 (D), D4^−/−, rd1/rd1 (E), and D5^−/−, rd1/rd1 (F) mice were harvested at postnatal day 2 and grown in organ culture for 27 days in vitro. Wild-type retinas maintained approximately five to six rows of cells in the ONL (A), while the ONL of untreated rd1/rd1 cultures, regardless of DR genotype, was reduced to approximately two to three rows (B-F). Quantitative analysis of photoreceptor survival as measured by ONL thickness is shown in (G). Black bars represent the genotypes shown in A-F and additional controls. Grey bars represent organ cultures from D2^−/−, D4^−/−, rd1/rd1 triple mutant mice treated with drugs as labeled. The number of cultures is indicated on the column for each condition; error bars indicate standard deviation. No significant difference is seen in the ONL thickness among rd1 organ cultures, regardless of DR genetic background or treatment. Similarly, no difference is seen among rd1 heterozygous control organ cultures. Abbreviations: outer segments (OS); inner segments (IS); outer nuclear layer (ONL); outer plexiform layer (OPL); inner nuclear layer (INL); inner plexiform layer (IPL); ganglion cell layer (GCL). The scale bar represents 10 μm.