Scanning electron microscopic (SEM) observations showing the surface topology of control-, and di-h-HALI-treated LSEC. (A) SEM micrograph of a control LSEC shows the presence of numerous fenestrae grouped in sieve plates (arrow). The bulging area contains the nucleus (N). Scale bar, 2 μm. (B) High-power SEM micrograph of the fenestrated cytoplasm obtained after 60 minutes exposure to 100 nM di-h-HALI. Note a typical cytoplasmic unfenestrated area (asterisk), surrounded by circular rows of very small fenestrae (arrow), suggesting nascent fenestrae fanning out into the surrounding fenestrated cytoplasm. Scale bar, 250 nm. (C) Shows a SEM micrograph of a LSEC treated with 100 nM di-h-HALI for 120 minutes, revealing a substantially increased number of fenestrae (large arrow). Thin nonfenestrated cytoplasmic arms (arrowheads) divide the cytoplasm into large sieve plates. In the fenestrated cytoplasm, small cytoplasmic unfenestrated areas devoid of connected fenestrae rows could be observed (small arrow), nucleus (N). Scale bar, 2 μm.