Fig. 4. Frequency distribution of mandible length in 18.5 dpc embryos. Distribution of mandible length in N2 wild-type embryos (n=30) chimeras crossed with wild type B6 females (A), heterozygous N2 mutants (n=200) crossed with wild-type B6 females (B) and heterozygous N3 mutants (n=200) backcrossed twice with wild-type B6 females (C).