Core Findings - The study demonstrates that the axolotl can regenerate its thymus completely after surgical removal, a process that occurs without any remaining thymic tissue [3][7]. - Within 7 days post-surgery, thymic structures begin to reappear, and by 35 days, the regenerated thymus is nearly indistinguishable from a normal thymus in morphology, size, and cellular composition [7]. Functional Recovery - Experiments showed that the regenerated thymus can function normally; after transplantation into other axolotls, fluorescently labeled cells from the regenerated thymus migrated to the host's blood, spleen, and limbs within 3 days [9]. - A year later, it was found that only thymic epithelial cells were from the donor, while all mature lymphocytes originated from the host, indicating that the regenerated thymus can recruit host hematopoietic progenitor cells to develop into functional T cells [9]. Molecular Mechanisms - The regeneration process involves complex cellular signaling, with two key signaling pathways identified: Bone Morphogenetic Protein (BMP) and Midkine (MDK) [10]. - MDK plays a crucial role in the early stages of regeneration, with expression beginning 1-3 days post-injury, prior to the reappearance of thymic epithelial cells [10]. Scientific Significance - This research confirms the complete regenerative capability of lymphoid organs in vertebrates, challenging previous scientific beliefs about the limits of organ regeneration in vertebrates [12]. - Understanding the molecular mechanisms of axolotl thymus regeneration may provide insights for developing therapies to promote thymus regeneration in humans, particularly for patients who have undergone thymectomy due to conditions like myasthenia gravis or cancer [13].