Fig. 2. Skeletal phenotype of Bmpr2^E2/E2 mutants. (A-C) Three siblings from a litter dissected at E15.5 showing that mutants die at various stages of gestation. (A) wild type (WT), (B) mutant dead at E14.5, (C) mutant dead at E12, as judged by the extent of limb development. (D-F) Cleared skeletal preparations of two siblings, recovered dead at birth. Dorsal views of the base of the skulls of WT (D) and mutant (E) illustrate the major ossification delay of the interparietal bone (Ipar), and of the ventral processes of the cervical vertebrae 1-4, in particular of the atlas (At). Socc, supraoccipital bone. (F) Ventral views of the half vertebral columns of wild type (left) and mutant (right) showing the absence of the thirteenth rib in the mutant (asterisk). Thoracic (T1-T13) and lumbar (L1) vertebrae are numbered. Note the ossification delay of the ventral and lateral ossification processes of the vertebrae in the mutant.