in amphibians 2 times that of fish: in birds >10 times that of fish times of lamellar branching in fish
||Koudouna E et al., Evolution of the vertebrate corneal stroma. Prog Retin Eye Res. 2018 May64: 65-76. doi: 10.1016/j.preteyeres.2018.01.002 p.69 right column 2nd paragraphPubMed ID29398348
||Winkler M et al., A Comparative Study of Vertebrate Corneal Structure: The Evolution of a Refractive Lens. Invest Ophthalmol Vis Sci. 2015 Apr56(4):2764-72. doi: 10.1167/iovs.15-16584PubMed ID26066606
||Abstract: "Although the cornea is the major refractive element of the eye, the mechanisms controlling corneal shape and hence visual acuity remain unknown. To begin to address this question [investigators] have used multiphoton, non-linear optical microscopy to image second harmonic generated signals (SHG) from collagen to characterize the evolutionary and structural changes that occur in the collagen architecture of the corneal stroma." Primary source abstract: "Nonlinear optical (NLO) imaging of second-harmonic-generated (SHG) signals was used to image collagen and three-dimensionally reconstruct the lamellar organization in corneas from different vertebrate clades."
||P.69 right column 2nd paragraph: "The presence of lamellar branching doubled in amphibians (Fig. 9C, Bullfrog, lower panel, arrow), increased markedly in number and thickness in reptiles (Fig. 9D, Alligator), and was over 10 fold higher in number in birds (Fig. 9E, Falcon) compared to fish (primary source)."