Fig. 5. Dynamics of tangentially migration MGE-GFP neurons. (A,B) Time-lapse analysis of MGE-GFP cells in isochronic co-cultures moving radially down from the MZ to the CP (A) and from the CP to the MZ (B). The position and morphology of the migrating cells is shown at 15 minute time intervals. Note that in each case, the cells pause at the interface between the MZ and the CP before crossing into the new zone. (C) Illustration of the kinetics of migration of an E15 GE-GFP cell within the MZ. Each circle represents the position of the cell body every 15 minutes and reveals that the cell body translocates according to a saltatory mode of migration. (D) Trajectories of 23 MGE-GFP cells migrating within the MZ. Twenty out of these 23 cells migrate coherently from the lateral (left-hand side) to medial (right-hand side) aspect of the cortex. One cell (#3) migrates mediolaterally, one cell (#1) migrates down into the CP and two cells (#13 and #2) migrate from the CP to the MZ. (E,F) Morphological dynamics of the leading process during a change in the direction of migration. These cells, migrating within the IZ, make 90° (E) or 180° (F) changes in their trajectory in less than 2 hours (time interval is indicated below each drawings). Note that in each case, the turn is not initiated by the growth cone of the leading process, but instead by a second leading process that emerges from the cell body. (G) Example of an MGE-GFP cells crossing from the IZ to the CP. Note that the cell initially migrating in the IZ pauses for a prolonged period (arrowhead) before changing its trajectory by 90° and entering the CP. The arrows indicate the direction of migration. Conventions as in C. (H) Trajectories of six GE-GFP cells migrating within the IZ. Note that most cells migrate from a lateral (left) to medial (right) direction. One cell can be seen changing trajectories to enter the CP. Scale bar: 50 µm in A-D,G-H; 100 µm in E,F.