Probable transcription factor. Mediates lens formation in the embryo by promoting the proliferation of the specified lens ectoderm and suppressing its terminal differentiation. First expressed at the end of gastrulation (stage 13) in the anterior ectodermal placode. During intermediate neural plate stages (stages 14-16), expression expands to the presumptive nasal ectoderm (PNE) and the presumptive lens ectoderm (PLE). By stages 18-21, expression begins to deplete in the PNE, while intensifying in the PLE so that by late neural stages (stages 22), expression is restricted to the PLE. Throughout tailbud stages (stage 23-31), expression is maintained in the lens placode and lens vesicle. In the maturing lens (stage 32-onwards), expression is restricted to the anterior lens epithelium, where it remains during the tadpole stage. In tadpoles there is additional expression in the ventral midline of the pharynx. Expression continues in the adult eye. By pax6.