mice 3-5%: ferrets ~15%: human ≤~40% %
||Kutsarova E, Munz M, Ruthazer ES. Rules for Shaping Neural Connections in the Developing Brain. Front Neural Circuits. 2017 Jan 10 10: 111. doi: 10.3389/fncir.2016.00111 p.2 left column bottom paragraphPubMed ID28119574
||Petros, T. J., Rebsam, A., and Mason, C. A. (2008). Retinal axon growth at the optic chiasm: to cross or not to cross. Annu. Rev. Neurosci. 31, 295–315. doi: 10.1146/annurev.neuro.31.060407.125609PubMed ID18558857
||P.2 left column bottom paragraph: "Unlike amphibians, in which the retinofugal projection is almost exclusively contralateral, in mammals a fraction of the RGCs does not cross at the optic chiasm but projects to the ipsilateral hemisphere of the brain. This fraction ranges from 3% to 5% in mice, around 15% in ferrets to up to nearly 40% in humans (primary source). Interestingly, anterograde and retrograde tracing of RGCs also reveals a substantial transient ipsilateral projection during embryonic development in mammals and chicks, much of which is lost during subsequent maturation (Land and Lund, 1979, Dräger and Olsen, 1980, McLoon and Lund, 1982)."