Fig. 2. Spina bifida in PDGFR mutant embryos. Skeletal preparations of E18.5 embryos display defects in lumbar vertebrae formation. (A) Control, (B) PDGFR^CKO (C) PDGFR^PI3K/PI3K and (D) PDGFR^TKO. Headings at the top of each column indicate the bone isolated. L, lumbar; T, thoracic. The lumbar vertebral arches form normally in A and B but fail to progress in C and D. Vertebral arch development of the thoracic vertebrae and limbs was normal in all embryos. Arrows indicate the extent that Alcian Blue cartilage can be detected. Scale bars: 1 mm. Asterisks indicate location of bones lost during dissection. sp, spinous process; l, lamina; vb, vertebral body; r, rib. Data representative of skeletal preparations performed on E18.5 and P1 embryos: wild type (n=10); PDGFR^CKO (n=4); PDGFR^PI3K/PI3K (n=10); and PDGFR^TKO (n=9).