This is a phase micrograph at 400X magnification of structures formed by a phospholipid in water. Phospholipids are the primary component of cell membranes, the essential boundaries between the cell and its environment. When isolated and exposed to water, most phospholipids can self-assemble into membranous structures. This particular lipid forms tubules called myelin figures, which curl up into the double helix seen in the micrograph. Lipids are colorless, so the NIH Image program was used to add color and contrast.