A new study presents a detailed cellular atlas of the developing coronal suture, the one most commonly fused as a consequence of single gene mutations, leading to birth defects such as craniosynostosis. With an aim toward advancing new interventions for patients, researchers created the first detailed cell-by-cell description of how this suture develops. They identified 14 distinct types of cells in and around the developing suture and new genes that may be involved in generating and maintaining the stem cells that grow the skull bones on either side of the suture.