Figure 1. Phenotypic analysis of Twist-1(+/–) tissues. First maxillary molars at Day 1, von Kossa stain showing an earlier onset of organic matrix and mineral deposition (arrows). (A) = Twist-1(+/+); (B) = Twist(+/–). Hematoxylin and eosin stain of maxillary incisor (C) and alkaline phosphatase activity around blood vessels in a consecutive section from D7 Twist-1(+/–) heads (D). Signals for Dspp (E) and Col I (F) in D21 Twist-1(+/–) maxillary incisors. Dentin-like deposits within a Twist-1-deficient pulp, Masson’s trichrome, D45 first mandibular molar (G,H).