Applying multiphoton imaging to the study of membrane dynamics in living cells

The endomembrane system of a cell is a highly dynamic, ephemeral structure that is difficult to visualize. Reconstructions from sections of fixed mate rial can provide high-resolution information on intercellular membrane arch itecture, but such techniques are fraught with artifacts and are of little help in understanding the dynamics of intracellular membrane traffic. Recen tly, the availability of fluorescent membrane probes and the development of techniques for optically sectioning intact specimens have allowed glimpses of membrane dynamics to be visualized in living tissue. In this review we discuss the potential of a new optical sectioning technique, multiphoton im aging, for visualizing membrane dynamics in living cells. Multiphoton micro scopy offers an unparalleled ability to obtain images from deep within spec imens while minimizing the effects of phototoxicity.