Research we covered in our #ARDD2025 field notes (linked below) is now published. @MaxYunLab showed axolotls can regenerate their thymus de novo after complete removal. Not partial regrowth from remnants like mammals can often manage, but full reconstruction. FOXN1, the transcription factor mammals need for thymus development, turns out to be dispensable for axolotl thymus regeneration. Midkine signaling appears to drive it instead. This is relevant for longevity because in mammals, the thymus shrinks with age, taking T cell production and immune function with it. Axolotls skip this process entirely, maintaining their thymus throughout life with roughly flat mortality risk. Understanding how they pull that off could eventually point toward ways to restore thymic function in aging humans.