Fig. 1. Stereotyped dynamic behavior of tangentially migrating interneurons. (A,B) Different morphologies of interneurons derived from the medial ganglionic eminence (MGE). (C) Experimental paradigm. NCx, neocortex. (D) Migration of MGE-derived cells in E13.5 dsRed-electroporated slice after 36 hours in culture. (E) Time-lapse sequence of a dsRed-electroporated interneuron (asterisk) migrating from the subpallium to the cortex in a slice culture. Time is depicted in hours: minutes. The bifurcation point of the leading process is marked by a broken blue line. The last frame in the sequence shows superimposed images of the frame t=0:00 (green) and t=0:52 (red). (F,F') Time-lapse sequence of a dsRed-electroporated interneuron migrating through the subpallium in a slice culture. This neuron was recorded for more than 7 hours to analyze several migratory cycles; only selected frames are displayed (see Movie 1 in the supplementary material for a complete movie version). The bifurcation points are marked by broken blue lines, and each leading process branch is coded with a colored arrowhead. Small arrows indicate small very transient processes. The drawings in F' illustrate the morphology of this cell for each of the frames shown in F. Scale bars: 20 µm in A,B,E-F'; 300 µm in D.