Fig. 7. NF-B is needed for secondary zigzag hair development, where it may also be regulated by TROY. (A) Upper panel: cryosections of E17.5 and P0 wild-type and c^IBN (N) mice, stained with Haematoxylin/Eosin. Lower panel: hair follicle numbers of E17.5 embryos [wild type, c^IBN (N); n=3 each] and newborn (P0; n=9 c^IBN, n=6 wild type) were counted per microscopic field (mf). Mean values were calculated and presented in bar graphs, including standard deviations. P values show a significant difference: ^*P<0.0158 versus wild type. for E17.5, and P<0.0001 versus wild type for P0. At P0, the mean value reveals 50% less hairs in c^IBN mice compared with wild type: 38/mf in c^IBN versus 75/mf in wild type. (B) The different developmental stages of hair follicle development (stage 1, placode – early bulbous peg stage 5, indicated to the left of the table) in wild type and c^IBN (N) mice at E17.5 and P0 are presented in percentage (%) of total number of hairs. (C) In situ hybridization of sagittal skin sections of E14.5, E15.5, E17.5 and P0 embryos using a TROY antisense probe. Broken line indicates the boundary between epidermis (E) and dermis (D). Arrows indicate placodes and (at P0) the matrix of a guard hair follicle.