Apical cytoskeletons in MTECs revealed by UHVEMT and thin-section electron microscopy (EM). (A) Selected tomographic slices showing the pattern-specific distribution of MTs (green lines) and intermediate filaments (IFs; arrowheads). Note the thick bundles of IFs in the floret pattern. Microtubule lines were drawn from a 3D reconstruction and superimposed on a single cross section. See also Videos 4–8. (B) Thin-section EM image of HMM-treated MTECs at ALI 28 d (right). Actin filaments are decorated with HMM showing the typical arrowhead patterns (black arrowheads), whereas IFs are not decorated (white arrowheads). Arrow shows MTs. High-magnification image of actin filaments decorated with HMM (left). Bars, 500 nm.