Transcription factor involved in anterior and eye development. Promotes the differentiation of both rod and cone photoreceptors cells in the retina. Together with other retinal homeobox proteins, acts as an effector of a cellular clock which, depending on cell cycle progression, establishes the generation of distinct retinal neuronal cell types. Acts synergistically with nrl to activate the rhodopsin promoter. Promotes the formation of anterior regions and represses the formation of posterior structures during development. Initially expressed in the Spemann organizer of early gastrula embryos. Expression in the organizer begins to decrease during late gastrulation and has disappeared by stage 11.5. Expression then persists and intensifies in the anterior neuroectoderm. Exhibits a dynamic expression pattern during neurulation and by neural tube closure (stage 20), expression is restricted to the cement gland anlage and epiphysis (pineal gland) anlagen. During tailbud stages, expression in the cement gland decreases and from stage 24, expression appears in the neural retina. By stage 37, expression becomes restricted to the outer and inner nuclear layers of the retina and the ciliary marginal zone (CMZ; the source of retinal growth). In mature embryonic retinas (stage 42), expressed preferentially in photoreceptors and in a subset of bipolar cells. Translation occurs during late retinogenesis and requires cell cycle progression with the timing of translation paralleling that of the generation of photoreceptor cells. In the CMZ, translation begins in early post-mitotic cells.