(A–E) Hematoxylin–eosin (H&E) staining of P21 retina sections show that photoreceptor OS layer is absent in all mutant retinas except CrxE80A/+. OS: outer segment; ONL: outer nuclear layer; INL: inner nuclear layer; IPL: inner plexiform layer; GCL: ganglion cell layer. Scale bar, 100 µm. (F–J) Rhodopsin (RHO, red) immunostaining is present in CrxE80A/+, CrxE80A/A, and CrxK88N/+ retinas and absent in CrxK88N/N retina. Cone arrestin (mCAR, green) immunostaining is absent in all mutant retinas. Nuclei were visualized by (4',6-diamidino-2-phenylindole) DAPI staining (blue). Scale bar, 100 µm. (K–M) The ERG responses recorded from 1 month mice. Error bars represent the standard error of the mean (SEM, n ≥ 4). p-value: Two-way analysis of variance (ANOVA) and Tukey’s multiple comparisons. ****p ≤ 0.0001. ns: >0.05.