Fig. 5. Effects of epidermal-specific deletion of Bmpr1a on the histology of postnatal anagen hair follicles, localization of phospho-SMAD1/5/8, and expression of hair follicle differentiation markers. (A,B) Histology of dorsal skin from K14-Cre40; Bmpr1a^cl/+ control littermate (A) and K14-Cre40; Bmpr1a^cl/cl mutant (B) at P8. Nuclei in the center of a mutant follicle are indicated by an arrow (B). (C,D) Histology of mid-ventral skin from bcre-32; Bmpr1a^cl/+ control littermate (C) and bcre-32; Bmpr1a^cl/null mutant (D) at P8. (E,F) Anti-phospho-SMAD1/5/8 immmunofluorescence of P8 dorsal skin from K14-Cre40; Bmpr1a^cl/+ control littermate (E) and K14-Cre40; Bmpr1a^cl/cl mutant (F). Staining is present in nuclei of IRS and hair-shaft precursors in control follicles (yellow arrows; E) but is much reduced in mutant follicle epithelium (F). Weak staining is present in mutant dermal papillae and in a few epithelial cells close to the epidermis (yellow arrows). (G-L) Immunofluorescence of P8 dorsal skin from K14-Cre40; Bmpr1a^cl/+ control littermate (G,I,K) and K14-Cre40; Bmpr1a^cl/cl mutant (H,J,L) using AE13 (G,H), AE15 (I,J) and anti-keratin 17 (K,L) antibodies. (M,N) Immunofluorescence of P8 mid-ventral skin from bcre-32; Bmpr1a^cl/+ control littermate (M) and bcre-32; Bmpr1a^cl/null mutant (N) using anti-keratin 6 antibody. Yellow arrows indicate the hair shaft (G), IRS and medulla (I), and outer root sheath (K-N). White arrow indicates epidermal staining (N). Immunofluorescence signals are red in E-L and green in M,N. Nuclei are counterstained with Hoechst 33258. Scale bars: in D applies to A-D; in F applies to E,F; in N applies to G-N.