Figure 1. Consecutive sections of a developing porcine incisor showing the stages of enamel formation. The top section is stained with toluidine blue, and the bottom section is immunostained with the 32-kDa enamelin antibody. Enamelin signal is observed in the enamel matrix throughout the matrix formation (secretory) stage and persists at the DEJ (arrowheads) during enamel maturation. Key: enamel, E; dentin, D; matrix formation stage, F; transition stage, T; maturation stage, M; arrowheads mark the DEJ. Adapted from reference (Uchida et al., 1991a).