Figure 3. Histology and immunohistochemistry of a 30-week implant. (A) H&E stain of dentin and enamel structures in a 30-week bioengineered tooth tissue (50X). (B) H&E stain of dentin, enamel, and putative cellular cementum in bioengineered tissue (400X). (C) H&E stain of enamel organ cells present in bioengineered tissues (400X). (D) H&E stain of enamel organ cells from a positive control porcine third molar tooth (400X). (E) Amelogenin expression in ameloblasts and enamel of 30-week bioengineered tissues. Positive brown stain is indicated by the arrows (400X). (F) Negative pre-immune control for amelogenin immunostaining (400X). (G) Bone sialoprotein (BSP) expression in dentin of 30-week bioengineered tissue (400X). Punctate expression pattern is indicated by arrows. (H) BSP expression in dentin of a positive control porcine third molar tooth (400X). Abbreviations as in Fig. 2 and: si, stratum intermedium; sr, stellate reticulum.