Figure 3. Chondrocytes in the Ulnaless ulna do not undergo hypertrophy upon blocking Ihh signaling.

Sections of E13.5 control (A, C, E, G) and Ulnaless forelimbs (B, D, F, H) that had been cultured for 4 days in control medium (A, B, E, F) or in medium supplemented with cyclopamine (C, D, G, H), were hybridized with the antisense probes for Ihh (A–D) and Col10a1 (E–H). Premature activation of Ihh as well as Col10a1 expression can be detected in the digits of cyclopamine treated control (C, G) and Ulnaless (D, H, yellow arrows) forelimbs. In contrast, in the ulna of Ulnaless mice Ihh and Col10a1 expression was not induced by cyclopamine (D, H, red arrows). 50x magnification (A–D), 80x magnification (E–H); R = radius, U = ulna.