Figure 7.

Retinal-derived neuregulin is required for normal OPC appearance. A–F, The ability of retinal conditioned medium to induce OPCs is blocked by NRG inhibitors. A, B, Control cultures of dorsal spinal cord contain few OPCs. C, D, OPCs are strongly induced by retinal CM. E, F, This induction is blocked with function-blocking anti-NRG antibody. G, Quantification of O4⁺ cells in cultures with different treatments. Error bars represent SD. H, I, Inhibition of NRG signaling between stage 21 (E3) and stage 29 (E6) significantly reduces the number of OPCs that develop at the floor of the third ventricle at stage 31 (E7). H shows a control animal, and I shows an anti-NRG-treated animal. J, The expression of NRG at the floor of the third ventricle is dependent on optic projections and is lost in eyeless animals. Scale bars (in D, I): 50 μm.