Beta-galactosidase staining of maxillary molars from PN7 collected from wild type, Enam^+/−, and Enam^−/− mice.

(A–C, H&E counter stained) No positive staining is consistently observed in wild type samples. (D–F, unstained) There are no detectable differences between wild type and Enam^+/− molars in terms of ameloblast organization, size of the ameloblasts and thickness of the enamel layer. (G–I) In Enam^−/− molars, bulges of enamel matrix along the cuspal slopes are associated with flattening ameloblasts. Non-polarized, lacZ positive cells are seen instead of ameloblasts and extending into the stratum intermedium area, sometimes incorporated in the abnormal aggregation of matrix and cellular components near the cusp tips in the null mouse samples.