Fig. 5. Tooth phenotypes of Pitx2 mutant allelic combinations. (A-D) Low-power view of coronal Hematoxylin and Eosin stained sections through molar teeth of 16.5 dpc wild type (A), Pitx2 abc^null; ab^hypoc (B), abc^null; ab (C), ab; ab (D). (E-H) High-power view of coronal Hematoxylin and Eosin stained sections through molar teeth of 16.5 dpc wild type (E), Pitx2 abc^null; ab^hypoc (F), abc^null; ab (G), ab; ab (H). (I-K) Parasagittal cryosections through 16.5 dpc embryos stained for lacZ. Wild-type (I) and abc^null; ab (J) show cap stage teeth, whereas abc^null; ab^hypoc (K) reveals a defect prior to cap formation (arrows). dc, dental cord; dp, dental papilla; e, epithelium: ek, enamel knot; mc, Meckel's cartilage; t, tongue;