Figure 7.

Absence of PTHrP expression in the Ihh ^−/− mutant. (A–D) 35S in situ hybridization for PTHrP and PTHrP-R on longitudinal sections through wild-type and Ihh ^−/− forelimb bones at 14.5 dpc. (A,B) PTHrP expression in articular perichondrium of wild-type (A) and Ihh ^−/− (B) humerus. No PTHrP expression is detected in the mutant. (C,D) PTHrP-R expression in wild-type (C) and Ihh ^−/− (D) radius and ulna. Note that in the wild-type, PTHrP-R expression is detected in maturing chondrocytes and in the perichondrium/periosteum. There is PTHrP-R expression in the mutant chondrocytes but not in the perichondrium. (h) Humerus; (u) ulna; (r) radius.