Interspecies differences in the assembly of the embryonic retina
Although the plan of the retina is well conserved across vertebrate species, there are considerable variations in cell-type diversity and cell-type number as well as in the organization and properties of the tissue that reflect differences in eye ontogenesis. Because high visual acuity requires a high ratio of retinal ganglion cells (RGCs) to photoreceptors, the proportion of progenitor cells recruited to produce RGCs in the developing retina contributes to the functional characteristics of the adult eye.
In diurnal birds, the ratio of RGC to photoreceptors is high (e.g., chicken) or very high (e.g., pigeon) and birds have a high visual acuity but a low sensitivity. In mammals this ratio is much lower and despite causing lower visual acuity, it increases sensitivity and had a beneficial influence on adaptation of mammals to night vision.
We explore how interspecies differences in the Atoh7-mediated transcriptional networks underlay variations in the production of RGCs in the chick, the pigeon and mouse retinas.