Morphology of Lyotropic Myelin Figures Stained with a Fluorescent Dye

Lyotropic myelin figures (MFs), i.e., long cylindrical structures formed by certain surfactants, owe their name to their resemblance to the biological membrane that covers nerve fibers. Herein, we used a strong bilayer-forming zwitterionic phospholipid stained by the Nile Red dye to study lamellar mesophases. Polarized optical microscopy and fluorescence confocal microscopy allowed us to investigate the morphology of myelin structures and determine the orientational order of amphiphilic molecules. The cross-sectional views reveal significant differences in the configurations of MFs within the liquid crystalline cell, as well as the details of a spontaneous and stimulated formation of branched lipid tubes. Our results provide insights into small-scale morphology and out-of-equilibrium structural changes in the multilamellar structures.