Fig. 6.

Distribution of PCNA-positive cells in the developing cortex. In E15 control animals, PCNA-positive cells (purple) are located in a typical band in the ventricular zone. In E18 control animals, labeled cells are also found at typical sites in the ventricular and subventricular zones. In E15 tish animals, PCNA-positive cells are found in both the ventricular zone and in the more superficial aspect of the developing cortex. In E18 tish animals, labeled cells are present in the ventricular and subventricular zones, and in a more superficial (heterotopic) position in the intermediate zone. A prominent band of PCNA-positive cells is present in the superficial aspect of the intermediate zone of the developing tish cortex at this time. Arrows indicate the pial surface of the cortex in the sections from the E15 animals. Scale bars: E15, 50 μm; E18, 200 μm.