||Fig.3. Shh is not a major regulator of dorsal midline fates.
Shh signaling was blocked by injection of Shh MO or by cyclopamine treatment (“−Shh” B, E, G, J, M, P) and activated by injection of Shh mRNA (“+Shh,” C, H, K, N, Q). Netrin expression in the floor plate was decreased in 42% of − Shh embryos (B, N = 387) and slightly upregulated in 44% of + Shh embryos (C, N = 139). Floor plate expression of Shh was slightly narrower in 29% of embryos with blockade of Shh signaling (E inset, N = 194). Perturbation of Shh signaling had no effect on notochord (AxPC, F–H and Tor70, I–Q) or hypochord (O–Q) or floor plate markers F-spondin and FoxA2 in the spinal cord of tadpoles (I–N). (A–H) Dorsal views, anterior up, with transverse bisection in inset (A–E). (G–O) Transverse vibratome sections through middle of spinal cord at tailbud stages.