Fig. 4. Chemoattractive activity of the neocortex on cells migrating from the MGE. (A) Schematic of the experimental paradigm used for E13.5 cells. (B) An example of the distribution of neurons originating in the MGE after 36 hours of co-culture with a neocortical explant. The presence of more MGE cells in the regions proximal to the cortex than distal to it indicates an attractive effect of the cortex on MGE cells. (C) Diagram of the scheme used to semiquantify the effects of the cortex on MGE migration [modified from Zhu et al. (Zhu et al., 1999)] and score of migration in co-culture experiments (with cortex) or in MGE alone experiments (control). MGE, medial ganglionic eminence; NCx, neocortex. Scale bar: 200 µm.