Effect of Netrin-1 on thalamic cells and axons. (A) In situ hybridisation for Netrin-1 mRNA (purple signal) on a coronal E14.5 forebrain section. (B,C) mRNA levels measured after 90 minutes exposure to Netrin-1 expressed relative to untreated controls. (B) LacZ mRNA levels in cultured BAT-gal thalamic explants. (C) β-actin, Epha4, and L1 mRNA levels in cultured thalamic explants. Transcript levels were measured using qRT-PCR and normalised to GAPDH with n = 3 for each condition. (D) Cultured thalamic explant immunostained for β-catenin with higher magnification of a growth cone in box shown in (E). (F) Growth cone β-catenin staining pixel intensity measured after 10 minutes, 1 hour, or 24 hours exposure to Netrin-1 expressed relative to untreated controls. For each condition values represent means for n = 84-95 growth cones randomly selected from 3 independent cultures each including thalamic tissue from several embryos Students t-test p values for ± Netrin-1 comparion indicated above histogram bars at each time-point. Scale bars: A = 200 μm; D, 100 μm; E, 5 μm.