Signaling: Contact-Mediated Signaling
Ectoderm-derived: Neural Crest; Ectodermal Placodes
Stage of Development: Embryo
This is a Stage 2 Brown anole, Anolis sagrei, embryo. The optic cup (oc) and lens (l) are beginning to develop. By Stage 4, the lens will undergo extensive differentiation and pigmentation will start to appear in the posterior retinal ectoderm. The choroid fissure (cf) is wide and should close by Stage 3.
The various components of the eye form from paracrine signaling involving reciprocal cross talk and induction. The optic vesicles, which protrude from the diencephalon (di), induce competent head surface ectoderm. The early optic cups form from the inward bending of the optic vesicles. The inner layers of the optic cups will become the prospective pigmented retinas and the outer layers will become the pigmented epithelium. Interactions between the lens placode and the prospective retinas result in the formation of the lenses. Neural crest cells will migrate into the region between the lenses and surface ectoderms to form the presumptive corneas.
Sanger, T.J., Losos, J.B., Gibson-Brown, J.J. A developmental staging series for the lizard genus Anolis: A new system for the integration of evolution, development, and ecology. Journal of Morphology, 2008, 269:129-137.
Gilbert, S.F. Developmental Biology. 9th Edition. Sunderland, MA, Sinauer Associates, 2010.