Fig. 2. Hair-specific ablation of the Bmpr1a gene in mice. Hair-Bmpr1a KO mice (right) lack external hairs at the limbs (arrowheads) at P30 (A). (B-D) The right hindlimbs of control mice at P30: (B) whole limb; (C) instep; (D) outstep. (E-G) Hindlimbs of P30 Hair-Bmpr1a KO mice: (E) whole limb shows an abnormal spreading of first digit and malformed claws in hindlimbs; (F) instep; (G) outstep. (H,I) HE stained section of forelimb from control mice (H) and Hair-Bmpr1a KO mice (I) at E15-16. TUNEL analysis in adjacent section of control mice (J) and Hair-Bmpr1a KO mice (K) (see boxed areas in H and I). The number of TUNEL-labeled nuclei in first digit of Hair-Bmpr1a KO mice limb at E15-16 was reduced (K) compared with control mice (J). In situ hybridization analysis of Bmpr1a using an exon 2-specific probe in a section from P30 control (L,M). The expression of Bmpr1a is efficiently abolished in the P30 Hair-Bmpr1a KO mice (N). c, cortex; irs, inner root sheath; m, matrix; me, medulla; ors, outer root sheath. Scale bars: 20 mm in A; 2 mm in B-G; 100 µm in H,I; 50 µm in J-N.