(A–C) SEM analysis of incisor enamel in mice treated with PBS or Notch antibodies in sagittal views. (A’–C’) Magnified views of red-boxed regions (A–C). Red arrowheads point to primary enamel rods and yellow arrowheads point to inter-rod enamel. Note the enlarged inter-rod enamel in anti-N1N2 incisors (B,B') compared to controls. In anti-J1J2 incisors, note the interrupted primary rod enamel and smaller size of inter-rod enamel (C,C') compared to controls. These observations highlight distinct roles of N1N2 and J1J2 in incisor enamel formation. DEJ, dentin-enamel junction; N1, NOTCH1; N2, NOTCH2; J1, JAG1; J2, JAG2.