FIG. 1.

Classic histology of the ameloblast/stratum intermedium complex. (A) Azan staining. Compare the perpendicular orientation of ameloblast (amel) and stratum intermedium (si) cell layers and the red color of the nuclei as revealed by Heidenhain's azan staining protocol. Enamel (en) appears in bright red and dentin (de) in bright blue. The odontoblasts (od) are located immediately adjacent to the pale blue predentin. (B) Masson–Goldner staining. Pierre Masson's connective tissue trichrome stain using Weigert's hematoxylin as a nuclear marker sharply distinguishes between elongated secretory ameloblasts (amel) and perpendicular stratum intermedium (si) cell orientation, while the enamel layer (en) is bright red and the dentin (de) appears in green color. (C) Periodic acid Schiff (PAS) staining of plastic sections. Note the identification of glycogens and other polysaccharides in the ameloblasts (amel) and at the dentin/enamel junction (en/de) and the absence of PAS staining in the stratum intermedium (si) and in the ameloblast secretory vesicles (arrow). (D) Polychromatic Paragon Epoxy stain to identify cellular details on semithin sections. Here the combination of toluidine blue and basic fuchsin resulted in intense dark violet staining of enamel (en) and dentin (de) mineralized tissues and high resolution at the interface between ameloblast (amel) and stratum intermedium (si) cell layers. (E, F) TNAP alkaline phosphatase enzyme immunohistochemistry. Note the strong staining for alkaline phosphatase in the stratum intermedium (si) and the absence thereof in the stellate reticulum (sr), ameloblast (amel), enamel (en), and dentin (de) cell layers (E). (F) is a higher magnification image.