Figure 3.

Fluorescence microscopy images of (a) the lipids extracted from Survanta, and (b) the extracted Survanta lipids plus 5 wt % SP-B. (Top row) Π = 26 mN/m; (bottom row) Π 34 mN/m. The images show discrete dark L_C phase domains in a continuous bright L_E phase. The domain size decreases and becomes less polydisperse with SP-B (compare a1 and b1 or a2 and b2). The domain size and number density also increase with surface pressure (compare a1 and a2 or b1 and b2). The bright spots in the images are surfactant bilayer aggregates in the subphase that are attached or associated with the L_E phase of the monolayer. SP-B increases the number of such domains, indicating its role in surfactant transport from the subphase to the interface.