Inside each cell, individual structures known as organelles perform key functions, but how these organelles contribute to the formation of tissues and organs is unknown. Groundbreaking research from the Campàs group at the Cluster of Excellence Physics of Life of TU Dresden now reveals that the cell’s nucleus controls the stiffness of eye and brain tissues, and even the ordered arrangements of cells in them. These results add a new role for the cell’s nucleus in tissue organization, well beyond its established role in genetic regulation.