The mouse model . (a) The mutation in homozygous causes a premature termination at aa residue Leu277. The mutated nucleotide is highlighted (b). Histology of control and mutant retina at P14, P21, and 3 months of age. OSs were absent at all ages in homozygous , and progressive thinning of IS, ONL, and OPL was observed. OSs: outer segments, ISs: inner segments, ONL: outer nuclear layer, OPL: outer plexiform layer, INL: inner nuclear layer. Scale bar 20 m.