Fig. 7. Invasion of the marginal zone in Vldlr mutants. (A,B) In situ hybridization for Cux2 on sagittal brain sections through the neocortex of adult wild-type mice (A) showed only few neurons in layer I, whereas many Cux2-positive cells were found in the marginal zone of Vldlr^-/- mice (B). (C-E) Sagittal brain sections through adult neocortex stained for NeuN similarly showed few neurons in wild-type animals (C) and ApoER2 mutants (D), but numerous cells in Vldlr mutants (E). Scale bars: 100 µm in A,B; 200 µm in C-E. (F) Stereological estimation of cell numbers in the marginal zone was performed in four animals of each group. Vldlr^-/- mice showed significantly more neurons (mean±s.e.m.) in the marginal zone compared with wild-type animals and ApoER2 mutant mice (P=0.029). No significant difference was found between wild-type animals and ApoER2 mutants.