Figure 6.

PIR⁺ T-cell progenitors in FL and FB emerge independently of Hes1. (A) RT–PCR analysis for expression of Notch-signal-related genes in cells of various stages of T-cell development. (B) PIR⁺ population in FL from 13 dpc fetuses of Hes1^−/− mice. Cells were four-color stained in the same way as in Figure 1A, and profiles of Lin⁻c-kit⁺ cells are shown. (C) Numbers of Sca-1^hi, PIR⁻ and PIR⁺ cells of FL, PIR⁺ cells of FB, and DN1 and DN2 cells of FT from 13 dpc fetuses of Hes1^−/− mice and Hes1^+/+ littermate mice, are shown. Error bars indicate SD in each group. (D–F) PIR⁺ cells in FL from Hes1^−/− fetuses are restricted to the T-cell lineage. Sca-1^hi cells, PIR⁻ cells and PIR⁺ cells of 13 dpc FL (a total of 100 cells for each group) from wild-type mice and Hes1^−/− mice were examined for T, B and myeloid cell potential by coculture with a dGuo lobe for detection of T-cell potential (D), coculture with TSt-4 for B-cell potential (E), and coculture with PA6 for myeloid cell potential (F), respectively, except that Thy-1 was used as a marker for the T-lineage cells in (D).