Visualizing membrane traffic in vivo by combined video fluorescence and 3Delectron microscopy

In studies of dynamic cellular processes, it would be ideal to be able to c ombine the capability of in vivo fluorescence video microscopy with the pow er of resolution of electron microscopy (EM). This article describes an app roach based on the association of these two techniques, by which an individ ual intracellular structure can be monitored in vivo, typically through the use of markers fused with green-fluorescent protein, and then analysed by EM and three-dimensional reconstruction methods, resulting in a 'snapshot' of its fine structure at any chosen time in its life cycle. The potential o f this approach is discussed in relation to various aspects of cell biology and especially to the question of the morpho-functional organization of th e intracellular membrane trafficking pathways.