Neural retina identity is specified by lens‐derived BMP signals

Abstract

SummaryDuring early development of the CNS, the anterior neural domain becomes restricted into different regions as: the telencephalon, the optic cup and the diencephalon. Simultaneously, lens progenitors are specified in the neural plate border. The molecular mechanisms that regulate the induction and maintenance of eye‐field cells, and the specification of neural retina cells in relation to other forebrain domains have been poorly defined. If prospective lens cells affect the early development of retinal progenitors have been debated. We have analysed these issues in intact chick embryos and explant assays. Our results show that BMP signals emanating from the lens ectoderm maintain eye‐field identity, inhibit telencephalic character and induce neural retinal cells. This highlights a novel role for BMP signals during the early development of the retina that is distinct from previously described roles in dorso‐ventral patterning and fate choice between neural versus RPE cells. Our findings link the requirement of the lens ectoderm for neural retina specification with the molecular mechanism by which cells in the forebrain become specified as neural retina by BMP activity.