Fig. 1.

Fluorescence microscopy of DPPC vesicles labeled with 0.09 mol% NBD-PE. (A) Vesicle above T_m in the L_α phase. (B, D, and E) Vesicles cooled below T_m into the phase. (Scale bars, 10 μm.) (C and F) Confocal images showing slices through a crumpled vesicle. (Scale bar for C, 5 μm; image width for F, 117 μm.) (G–I) Confocal images of vesicles in the phase dispersed in a 12-μM fluorescent dextran solution before crumpling. Some vesicles remain intact and appear black in the interior (G and H), whereas others show leakage and appear red inside (H and I). Note that the vesicle in I has a clear break in the membrane, as indicated by the arrow. (Scale bar, 20 μm.)