The goal of this study is to profile stromal cells comprising the human thymus to better understand how this critical organ of the immune system is generated and how it supports the development of T lymphocytes and induction of self-tolerance. Overall design: Stromal cells isolated from two fetal (19 and 23 gestational weeks), two postnatal (6 day old and 10 month old), and one adult (25 year old) thymic samples were analyzed by single-cell RNA sequencing using the 10X Genomics platform. Please note that the *H5AD files containing the preprocessed, normalized and annotated count data of three experiments have been added on Nov 19, 2021.