Fig. 8. The progeny of NGN3+ cells are mitotically active at E14, but they suppress Ngn3 expression. Ngn3-Cre-ER^TM; Z/AP embryos were given TM at E8.5-E10.5 and the mitotic status of HPAP+ cells was assayed by BrdU incorporation. Ngn3 expression and the differentiation of these HPAP+ cells was examined between E13.75 and E14 using NGN3 or NEUROD antibodies. (A) A clone composed of three HPAP+ cells (arrow), indicating that they are derived from a cell that expressed Ngn3. (B) An adjacent section to that in A shows these HPAP+ cells have incorporated BrdU. (C) HPAP staining (blue) and NGN3 protein staining (brown; with a polyclonal Ab). The cell indicated by the red arrowhead does not stain for NGN3 protein, whereas two other cells (black arrowheads) in this section are NGN3+. (D) An HPAP+ cell (blue stain, red arrowhead) that has differentiated and is expressing NEUROD protein (brown antibody stain). Other cells in this field are not HPAP+ but do stain for NEUROD. Scale bar: 8 µm.