Chinese researchers published a map on October 29, 2026, showing how human urinary and reproductive organs develop, how signals from nearby tissues may guide gonad formation, and a possible link between some gonadal support cells and the mesonephros.
The team studied male and female embryos at three stages of development. They combined maps showing where genes were active with analyses of individual cells, protein imaging and stem-cell models to keep information about where cells were located. The analysis distinguished 33 cell types and suggested that kidney-related cell groups separated earlier than the groups that form the adrenal glands and gonadal support cells.
At an early stage, the developing gonad received WNT, BMP and NCAM signals from nearby tissues, including the mesonephros and early adrenal tissue. In lab tests, a combination of related signals moved mesoderm cells produced from stem cells toward an early gonad-like state. This supports, but does not prove, a role for nearby tissues in gonad development.
The researchers also found rete cells expressing PAX8 at the boundary between the gonad and mesonephros. Their similarity to mesonephric cells raises the possibility that some gonadal support cells develop through this connecting tissue. The atlas also identified three groups of steroid-producing cells, with different roles in using cholesterol and making hormones.
The findings give a broader picture of how nearby organs develop together. The suggested cell origins and signaling relationships need further study.