Figure 2.

GRHL2 is predominantly expressed in progenitor cells in the postnatal pituitary. At p1 GRHL2 positive cells are mostly restricted to the intermediate lobe (IL) (A and M) and anterior lobe (AL) cleft cells (D and S) and a few GRHL2 positive cells are detected in the AL parenchyma (G, J and P). SOX2 is expressed in the cleft cells of the IL (B) and AL (E) cells of wild type pituitaries. A few SOX2 positive cells are detected in the AL parenchyma (H). GRHL2 is detected in the vast majority of SOX2 positive cells in both the IL (C) and AL (F and I). POMC is expressed in the AL parenchyma (K). GRHL2 expression is absent from POMC positive cells in the AL parenchyma (L). POMC is also expressed in dorsal IL (N). The majority of cells that express GRHL2 in the IL are not POMC positive (O and O′). A small subset of POMC positive cells appear to weakly express GRHL2 in the dorsal IL (O″, arrows). PIT1 is highly expressed in the anterior lobe parenchyma (Q). GRHL2 is absent from the majority of PIT1 positive cells but was detected in a small population of cells that weakly express GRHL2 (R). LH positive cells are confined to the AL parenchyma (T). Occasionally, cells double-labeled with GRHL2 and LHβ were detected in the AL but the majority of LHβ positive cells do not co-express GRHL2 (U). Arrows indicate double-labeled cells. Scale bar = 50 μm (A–U). Scale bar = 5 μm (O′ and O″). n=3–4.