Wnt5a and PCP/Neurogenesis Figure 8. The distribution of TH+ cells in the rostrocaudal and mediolateral axis is altered in Wnt5a2/2 mice. (A) At E12.5, there is a redistribution of TH+ cells in the VM, both in the rostrocaudal and mediolateral axis. (B) Three representative levels throughout the VM were measured for lateral spread of TH+ cells: rostral, medial and caudal. ImageJ was used to measure the distance between the two TH+ cells furthest apart in (D). (C) TH+ cells were quantified at regular intervals from rostral to caudal midbrain in (E–F). (D) TH+ cells are distributed much more broadly in anterior midbrain of E12.5 Wnt5a2/2 mice compared to WT (ANOVA, N = 3, p,0.001). (ANOVA with Bonferroni’s post test, Rostral WT vs Rostral Wnt5a2/2 p,0.001). (E–F) Rostrocaudal distribution of TH+ cells. (E) At E11.5 no difference could be seen between the distribution of TH+ cells in the anteroposterior axis of WT or Wnt5a2/2 mice. However, at E12.5 (F) and E14.5 (G) an altered distribution with a decrease in the number of TH+ cells in anterior levels and an increase in medial levels was seen (Two way ANOVA, for level and genotype, P = 0.0016 at E12.5, P,0.0001 at E14.5, N = 4). (H) The lateral expansion of TH+ cells at E12.5 was confirmed by in situ hybridization for Th, Pitx3 and DAT, two other markers of maturing dopaminergic neurons. doi:10.1371/journal.pone.0003517.g008 binding to N-cadherin leads to decreased cell adhesion, increased Shh signaling and proliferation [53]. We therefore suggest that the increase in Shh signaling (first detected at E11.5 by the regulation of Foxa2 and Lmx1a), may be induced by a decrease in the levels of N-cadherin protein and cell adhesion at earlier stages, when no other phenotype is apparent. In agreement with a role for Shh in regulating proliferation, we found an increase in the number of proliferating apical VZ progenitors and a lateral expansion of the PLoS ONE | www.plosone.org 10 October 2008 | Volume 3 | Issue 10 | e3517