Fig. 7. Mash1 but not Ptf1a is expressed during all stages of the cell cycle. To determine at which stages of the cell cycle Mash1 or Ptf1a are expressed, BrdU was injected at the indicated time points before analysis of E12.5 embryos. (A-D) Analysis of dorsal spinal cords with antibodies directed against BrdU (green) and Mash1 (red). (E-H) Analysis of dorsal spinal cords with antibodies directed against BrdU (green) and Ptf1a (red). (I-L) Analysis of dorsal spinal cords with antibodies directed against BrdU (green) and phosphorylated Histone 3 (red), a marker for M-Phase cells. (M) Schematic display of the expression of the transcription factors Mash1 and Ptf1a during cell cycle at E12.5 (PD cell located in progenitor domain; MZ cell located in mantle zone). Scale bars: 100 µm and 10 µm.