Anterior eye development in the brown anole, Anolis sagrei

Abstract

BackgroundAnterior eye development has been explored in different vertebrate species ranging from fish to mammals. However, missing from this diverse group is a representative of reptiles. A promising candidate to fill this void is the brown anole, Anolis sagrei, which is easily raised in the laboratory and for which genome editing techniques exist. Here we provide a detailed histological analysis of the development of the anterior structures of the eye in A. sagrei, which include the cornea, iris, ciliary body, lens, trabecular meshwork, and sclera ossicles. ResultsDevelopment of the anterior segment in Anoles proceeds as for other vertebrates with the lens forming first followed by the cornea, then the iris, ciliary body, trabecular meshwork, and sclera ossicles. The onset of these latter structures occurs first temporally than nasally. Unlike the eyes of mammals and birds, anoles possess a remarkably thin cornea, flat ciliary body, and a trabecular meshwork that lacks an obvious Schlemms canal. ConclusionsThis study highlights several features present in anoles and represents an important step towards understanding reptile eye development. Key FindingsO_LIThe anole cornea epithelium is thin, composed mainly of a single basal cell layer. C_LIO_LIThe ciliary body lacks a ciliary process. C_LIO_LIIris and ciliary body formation occur in a spatiotemporal fashion, developing first temporally then nasally. C_LIO_LIThe anole trabecular meshwork is composed of a spongiform tissue and lacks a Schlemms canal. C_LI