Centriole continuity: Out with the new, in with the old

Centrioles are essential microtubule-based organelles, typically present in pairs, which organize cilia and centrosomes. Their mode of biogenesis is unique for a subcellular organelle since, during cell division, each pre-existing centriole guides the formation of a new one, a process that is coordinated with DNA replication. After centriole duplication, the new centrosomes migrate in opposite direction and localize at each pole of the mitotic spindle. This singular dynamics led to think that centrioles were permanent self-replicating structures coordinating cytoplasm and nuclear division. This vision then fell gradually into disuse when centrioles were shown to be capable to form de novo, in the absence of a pre-existing structure, and to be actually dispensable for cell division. However, new data, which are reviewed here, have breathed new life into the old ideas.