Table 1.

Assessment of the frequency of P/P divisions

Age
E13E14E13+E14E15
In vivo*
   Ki67-positive/Nissl-positive90%83%87%56%
Surface divisions in slices
   Short culture
      Total two-cell clones154196
      Ki67-positive:Ki67-positive11 (73%)3 (75%)14 (74%)2 (33%)
      Ki67-positive:Ki67-negative4 (27%)1 (25%)5 (26%)2 (33%)
      Ki67-negative:Ki67-negative0 (0%)0 (0%)0 (0%)2 (33%)
Extended culture
   Total clones (2∼4 cells)70
      P/P57 (81%)
      P/N11 (16%)
      N/N2 (3%)
  • Daughter cells that did not divide beyond the time that many other daughter cells had divided were judged as neurons (N) in the extended culture.

  • * Fluorescent Nissl stain was used to visualize all cells in the cerebral wall. The proportion of Nissl-positive cells in the VZ and SVZ of the dorsal pallial region (photographed using a 40× objective lens) that were Ki67 positive (Fig. 1B) was calculated (n=546 cells at E13, 612 cells at E14, and 681 cells at E15)

  • Daughter cells generated at the ventricular surface were characterized by staining with anti-Ki67 within 4-7 hours from their birth (short culture, Fig. 1C) or by keeping them much longer (extended culture, Fig. 1D,E)