Researchers at the MDI Biological Laboratory have identified how zebrafish regenerate and reconnect new kidney filtration units after injury, revealing a coordinated cellular process that allows newly formed nephrons to integrate into the kidney’s existing tubule network. The study, published in the journal Development, shows that specialized cells at the connection site briefly adopt invasive behaviors—extending protrusions that initiate the physical link between new and old structures—while neighboring cells simultaneously divide and expand the growing tubule. The work also identifies intersecting signaling pathways, including canonical and non-canonical branches of Wnt signaling mediated by the receptor fzd9b, that orient the connection and regulate cell behavior. Understanding how zebrafish achieve this precise integration may help researchers overcome a major obstacle in regenerative medicine: enabling lab-grown tissues and organoids to connect into existing organs and become fully functional.