TEM micrographs of whole mount, formaldehyde prefixed, cytoskeleton buffer-extracted control LSEC (A), and di-h-HALI treated LSECs (B-F). (A) Low magnification showing the area containing the nucleus (N) and extracted cytoplasm. Note that the sieve plates are well defined by a dark border (arrowheads). Inside the sieve plates, fenestrae can be observed (small arrows). Scale bar, 2 μm. (B) Treatment with di-h-HALI for 10 to 20 minutes resulted in the appearance of small cytoplasmic unfenestrated areas of intermediate density (small arrows) lying in the neighbourhood of the perinuclear area (pn). Scale bar, 1 μm. (C) Within 30–60 minutes of treatment, small cytoplasmic unfenestrated areas of intermediate density (arrows) could be observed within the peripheral cytoplasm. Scale bar, 2 μm. (D) Examination at high magnification of such cytoplasmic unfenestrated area or FFC (asterisks) show a peculiar structure, with centrally very small fenestrae (small arrow) which form rows of fenestrae with increasing size (large arrow), radiating into the surrounding cytoplasm as a whirlwind. Note the presence of microtubule bundles closely running along the sieve plates (arrowheads). Scale bar, 1 μm. (E) Low magnification showing the cell nucleus (N) and the highly fenestrated cytoplasm (small arrow) after 120 minutes of di-h-HALI treatment. Note the thin cytoplasmic arms (arrowheads) which run from the nucleus into the cytoplasm. Inactive FFCs (arrows). Scale bar, 5 μm. (F) Higher magnification of the fenestrated cytoplasm shows the presence of FACRs (arrow). From these rings, small interconnecting filaments (arrowheads) seem to cross-link the surrounding cytoskeleton. Scale bar, 250 nm.