Analysis of the 3D basement membrane structure. (A) Confocal images of the hair follicles enclosed by a continuous line-like BM structure. Images show z-stack maximum projection images and single z-plane images of developing hair follicles with a continuous line-like BM structure at the tip (observed in 9 out of 13 follicles examined), lower stalk (observed in 12 out of 13 follicles examined), and upper stalk regions (observed in all 13 follicles examined). These hair follicles were developed in cultured skin explants from E12.5 embryos of eGFP-Col4a2 mice (n = 13 follicles from five explants, each from an independent experiment). Scale bars: 10 μm. (B) Confocal z-stack maximum projection and single z-plane images of the hair follicles exhibiting pores (arrowheads) in its lower part. The BM with pores (a dotted rectangular area) is magnified. Scale bars: 10 μm. (C) Confocal z-stack maximum projection and single z-plane images of the hair follicles treated with an MMP inhibitor (batimastat). No clear pore structures were observed in the 13 MMP inhibitor-treated hair follicles examined. (n = 13 follicles from five explants, each from an independent experiment for the inhibitor-treated condition). Scale bars: 10 μm.