Utrastructural features of MMECs and a HUVEC. (A-G) MMECs. (H) HUVEC. (A,G) Two MMECs showing very thin cytoplasmic regions arranged in the form of a tubelike structure (arrows). (B) Another cell showing numerous and parallel arranged cisternae of rough endoplasmic reticulum (arrow). (C-F) Cells showing bundles of thickened microfilaments, located to nucleus (C-D, arrows) or to subcortical plasma membranes (E, arrowhead), or scattered in the cytoplasm (E, arrow), or showing disarranged microtubules (F, arrow). (H) A HUVEC showing lipid droplets and a normal distribution of cytoskeleton organelles. Scale bar, 2.7 μm (A); 0.4 μm (B); 0.8 μm (C); 0.2 μm (D); 0.4 μm (E-F); 0.3 μm (G); and 0.7 μm (H).