Figure 4

Ectopic cells in the INL of homozygous Eml1^tvrm360 mice are rod and cone photoreceptors. (a–c) Retinal sections immunostained with photoreceptor-specific antibodies: rhodopsin (RHO), cone arrestin (cARR), blue opsin (OPN1SW) and green opsin (OPN1MW). Retinal staining at P8 and P14 shows mislocalization of visual pigments in the INL of Eml1^tvrm360 mutants. (a) White arrow demarcates presumptive OPL while asterisks show mislocalized rod opsin in the GCL at P8. (b) Shortened cone processes in the ONL are revealed by cone arrestin staining which highlights the position of the cone pedicules in the presynaptic layer and cone cell bodies on the apical side of the ONL. (c) White arrows indicate mislocalized blue opsin pigment in the INL of Eml1^tvrm360 mutant retinas. (d) Immunostaining with synaptic markers, SYPH and CTBP2 (ribeye) shows ectopic synapses in the INL of homozygous Eml1^tvrm360 mice at P14. Closer view of boxed region in INL is shown in the top right inset (SYPH, synaptic vesicle; CTBP2, synaptic ribbon). (e) White asterisks indicate ectopic synapses (CTBP2) found adjacent to mislocalized photoreceptors (REC, recoverin) in mutant retinas. ONL, outer nuclear layer; INL, inner nuclear layer; OPL, outer plexiform layer. Scale bars: 20 µm (a,c–e); 10 µm (b).