The organization and maintenance of the internal structure of cells, both eukaryotic and prokaryotic, are essential to their survival. Specialized compartments are either delimited by membranes (mitochondria, nucleus, endoplasmic reticulum, chloroplasts…), or formed by liquid phase separation phenomena (nucleolus, nuclear or cytoplasmic bodies, viral factories…). Exchanges between these compartments ensure the coordination of their activities, which involves complex and dynamic networks of macromolecules and macromolecular assemblies (cytoskeleton, motors, transporters, lipid or chromatin phases, membrane- membrane contacts…). The dysfunctions of this organization are at the origin of many pathologies.