Fig. 1.

Phenotypic comparison of E12.5 embryos from wild-type (A, embryo 1), heterozygous (A, embryo 2), and homozygous (B, embryos 3 and 4) tph1 mothers. Embryos displayed no obvious macroscopic anomalies except for an overall size reduction in embryos obtained from tph1−/− mothers (embryos 3 and 4). Size reduction was evaluated by measuring the CRL of the embryos. An overall 15–30% reduction was observed in the mutant embryos obtained from tph1-null mothers. CRL values are 7.8 mm (embryo 1), 7.7 mm (embryo 2), 6.8 mm (embryo 3), and 7.0 mm (embryo 4). (Scale bars: 0.25 cm.)