Perls’ blue staining of rat maxillary incisor. Sagittal section of 4-week old rat maxillary incisor was stained with Perls’ Prussian blue for detection of iron and counterstained with nuclear fast red. Panel A: Whole incisor observed under stereoscope with 12.5 x magnification. Panels B1 - B3: Boxed regions (1-3) in panel A are shown with 100x magnification. Panels C1, C2a - 2c, and C3a - 3d: Progression from secretory stage amelogenesis (C1) to late maturation stage amelogenesis (panel C3d) with 630x magnification. 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.