Figure 5

Normal CA growth in Ntn1 ^pMN-Ko mice. (a,b) Ntn1 ISH in whole-mount preparations of E12.5 control (Olig2 ^+/Cre ;Ntn1 ^+/flox) (a) and Ntn1 ^pMN-Ko (b) mouse hindbrains (control, n = 6; Ntn1 ^pMN-Ko, n = 6). In Ntn1 ^pMN-Ko mouse hindbrains, Ntn1 hybridization signals are not detected in pMN adjacent to the FP (arrowheads). (c,d) Robo3 immunostaining in whole-mount preparations of E12.5 control (c) and Ntn1 ^pMN-Ko (d) mouse hindbrains (control, n = 8; Ntn1 ^pMN-Ko, n = 5). In both genotypes, Robo3⁺ axons grow ventrally and reach the midline. (e,f) DiI labeling of CAs in whole-mount preparations of E12.5 control (e) and Ntn1 ^pMN-Ko (f) mouse hindbrains (control, n = 8; Ntn1 ^pMN-Ko, n = 6). DiI-labeled CAs grow towards the midline (arrowheads) and cross it in both genotypes. (g,h) Histograms representing the fluorescence intensity of Robo3⁺ axons within the ventral one-fourth of the hindbrain normalized to that in the preparation (control, n = 8; Ntn1 ^pMN-Ko, n = 5; ^n.s P > 0.05, Mann–Whitney U-test; P = 0.724) (g) and the fluorescence intensity of DiI-labeled axons within the FP normalized to that at the implantation site (control, n = 8; Ntn1 ^pMN-Ko, n = 6; ^n.s P > 0.05, Mann–Whitney U-test; P = 0.573) (h), respectively. Error bars indicate SEM. There are no significant differences in both Robo3⁺ and DiI-labeled axon growth between genotypes. Dorsal is upwards and rostral is towards the left. Hindbrains at the rhombomere 6 to 8 level are represented. The bar in (a), (c) and (e) apply to (a,b), (c,d) and (e,f), respectively.