Fig. 5. Ihh signalling from secondary chondrocytes. (A,D,G,) Alcian Blue/Chlorantine Fast Red stained controls. (A-C) At e11, Ihh is expressed by SCs (B), but, as shown on an adjacent section (C), ptc2 expression is at the limit of detection in the germinal region (white arrowhead); however, it is expressed in the feather buds (FB; inset in C). (D-F) At e12, Ihh is expressed by SCs (E), and ptc2 (F) is expressed in the germinal region (arrowhead). (G-I) At e14, the relationship between Ihh (H) and ptc2 (I) expression is maintained, brackets indicate extent of the germinal region. Scale bars: 100 µm.