Immunohistochemical staining of Fth in maxillary incisor. Sagittal section of 4-week old rat maxillary incisor was stained with anti-Fth antibody and counterstained with hematoxylin. Panel A: Whole incisor observed under stereoscope with 12.5x magnification. Panels B1-B3: Boxed regions (1-3) shown in panel A are shown with 100x magnification. Panels C1, C2a - 2c and C3a - 3d: Progression from secretory stage amelogenesis (panel C1) through late maturation stage amelogenesis (panel C3d) with 630x magnification. Late stage ameloblasts and the overlying papillary layer cells are the most highly staining cells in this progression. Enamel organ cells (ameloblasts, stratum intermedium, stellate reticulum and papillary layer cells) are labeled in panels C1 and C3d. The arrow in panel C3d shows a blood vessel surrounded by papillary layer cells. The following abbreviations are used: am, ameloblasts; si, stratum intermedium; sr, stellate reticulum; pl, papillary layer. Scale bars: A, 1 mm; B1-B3 and C1-C3d,10 μm.