The optic vesicle promotes cornea to lens transdifferentiation in larval Xenopus laevis

The outer cornea and pericorneal epidermis (lentogenic area) of larval Xenopus laevis are the only epidermal regions competent to regenerate a lens under the influence of the retinal inducer. However, the head epidermis of the lentogenic area can acquire the lens-regenerating competence following transplantation of an eye beneath it. In this paper we demonstrate that both the outer cornea and the head epidermis covering a transplanted eye are capable of responding not only to the retinal inducer of the larval eye but also to the inductive action of the embryonic optic vesicle by synthesizing crystallins. As the optic vesicle is a very weak lens inductor, which promotes crystallin synthesis only on the lens biased ectoderm of the embryo, these results indicate that the lens-forming competence in the outer cornea and epidermis of larval X. laevis corresponds to the persistence and acquisition of a condition similar to that of the embryonic biased ectoderm.