Fig. 5. In vivo NF-B activity is downstream of Eda A1/EdaR. (A) Gal NF-B reporter mice ((Ig)_3xconalacZ, gal) were mated into c^IBN (IBN, N), downless (dl, mutant EdaR) or tabby (ta, mutant Eda A1) mice, and analysed by X-Gal test at the time point of guard hair placode initiation. Upper panels, E14; lower panels, E15. Gal x c^IBN mice only revealed some background staining close to the eye and elbow. In Gal x downless and x tabby embryos, X-Gal staining was absent in the placodes, but present in blood vessels (see lower left insets). (B) Technovit sections of X-Gal stained P0 skin of the same matings as indicated in the top left. For X-Gal staining in newborn wild-type Gal skin, see Fig. 2B. (C) In situ hybridization of sagittal paraffin sections of wild-type, c^IBN and downless (dl) embryos at indicated time points, using EdaR, mouse IB, Eda A1 and human IB antisense probes. vib., vibrissae. Arrows indicate follicle placodes and (in Eda A1) interfollicular epidermis. 0/1–3, developmental stages of hair placode.