Figure 5

Correlation of Pax6 levels in progenitors in different phases of the cell cycle. Flow cytometric analyses of Pax6 levels among postmitotic cells and cycling progenitor cells at E7 (HH stage 32). (A) Cell density profile of total retinal cells labeled with Pax6 and a combination of neuronal markers, including Brn3a, Islet1/2, AP2a, and Visinin. Neuronal marker-positive cells (above the purple line) represent G0 cells; and neuronal marker-negative cells (below the purple line) are mostly progenitor cells. (B) Cell density profile of total retinal cells labeled with a combination of neuronal markers (same as in (A)), BrdU, and Pax6. Gated areas 'a' and 'c' represent postmitotic G0 phase cells; gated area 'b' represents BrdU⁺ S phase cells; gated area 'd' consists of G1, G2, and M phase cells. (C, D) Cell density profiles of G1 and G2/M phase cells (C) (as gated in area 'd') and S phase cells (D) (as gated in area 'b' in (B)) according to Pax6 levels and DNA content. In (D), G1 and G2/M cells are shown in the background as a reference to S phase cells. (E) Merged flow cytometry profiles of G1 (red), G2/M (green), and S (blue) phase progenitor cells according to Pax6 levels and DNA content. Flow cytometry profiles shown in (A, B) were generated with >85,000 cells. Numbers within each panel indicate percentage of gated cells among total cells.