Three-dimensional STORM imaging of CCPs in a cell. (A) Conventional direct immunofluorescence image of clathrin in a region of a BS-C-1 cell. (B) An x − y cross section (50-nm thick in z) of the 3D STORM image of the same area, showing the ring-like structure of the periphery of the CCPs at the plasma membrane. (C) Serial x − y cross sections (each 50-nm thick in z) and x − z cross sections (each 50-nm thick in y) of a CCP. (D) An x − y and x − z cross section presented in 3D perspective, showing the half-spherical cage-like structure of the pit. (Adapted, with permission, from Huang et al. 2008b, ©AAAS.)