The invention relates to a family of cyanine dyes selected from(see formula I)(see formula II)and(see formula III)which fluoresce in the far red and near infra red wavelengths of the spectrumand preferablypossess lipophilic side chains. The dyes of the invention are soluble incommerciallyavailable membrane staining vehicles, are useful as probes for rapidlystaining lipophilicstructures such as membranes in cells or isolated from cells, and are wellretained therein.Methods of using the dyes to detect stained cells both in vivo and in vitroare also disclosed.
