Thanks to the use of autofluorescent proteins, cell biologists are now able to observe and study the evolution of the volumetric content of live cells through time sequences of 3 D images (also called 4 D images). We present in this paper 4DReAM a tracking framework based on a deformable model, and how we apply it in cell biology to understand, describe, explain, in addition to interactively visualize and analyze the evolution of structures enclosed one in another, at different levels in the cell: proteins, nucleoli and nucleus. This deformable model, defined as a triangulated mesh, can automatically adapt its topology to fit the splits and merges of the biological objects. The usefulness of 4DReAM is illustrated on experimental results from different 4 D images acquired by confocal microscopy.