Tools for visualizing cell-cell 'interactomes'.

Cellular communication drives diverse aspects of organismal biology ranging from immune function to memory formation. The mechanisms by which cells transact information in vivo, though, are not completely understood. This is due, in part, to a lack of tools for observing collections of cells in their native habitats. New optical probes are being crafted to image networks of cell-cell interactions (i.e., 'interactomes') in tissues and live organisms. Examples of these probes-and their use in visualizing cell contacts and macroscopic cell networks-are highlighted.