a Living Stock Collection. Located at the University of Kentucky, the AGSC is dedicated to supplying genetically well-characterized axolotl embryos, larvae, and adults to laboratories throughout the United States and abroad. An NIH-funded NCRR grant has led to the establishment of the Ambystoma EST database, the Salamander Genome Project (SGP) that has led to the creation of the first amphibian gene map and several annotated molecular data bases, and the creation of the research community web portal. In 2022, a first spatiotemporal map revealed key insights about axolotl brain regeneration, also providing the interactive Axolotl Regenerative Telencephalon Interpretation via Spatiotemporal Transcriptomic Atlas . Frog model Anurans (frogs) can only regenerate their limbs during embryonic development. Reactive oxygen species (ROS) appear to be required for a regeneration response in the anuran larvae. ROS production is essential to activate the Wnt signaling pathway, which has been associated with regeneration in other systems. Once the limb skeleton has developed in frogs, regeneration does not occur (Xenopus can grow a cartilaginous spike after amputation). The adult Xenopus laevis is used as a model organism for regenerative medicine. In 2022, a cocktail of drugs and hormones (1,4-DPCA, BDNF, growth hormone, resolvin D5, and retinoic acid), in a single dose lasting 24 hours, was shown to trigger long-term leg regeneration in adult X. laevis. Instead of a single spike, a paddle-shaped growth is obtained at the end of the limb by 18 months. Hydra Hydra is a genus of freshwater polyp in the phylum Cnidaria with highly proliferative stem cells that gives them the ability to regenerate their entire body. Any fragment larger than a few hundred epithelial cells that is isolated from the body has the ability to regenerate into a smaller version of itself. The high proportion of stem cells in the hydra supports its efficient regenerative ability. Regeneration among hydra occurs as foot regeneration arising from the basal part of the body, and head regeneration, arising from the apical region. Regeneration tissues that are cut from the gastric region contain polarity, which allows them to distinguish between regenerating a head in the apical end and a foot in the basal end so that both regions are present in the newly regenerated organism. Head regeneration requires complex reconstruction of the area, while foot regeneration is much simpler, similar to tissue repair. In both foot and head regeneration, however, there are two distinct molecular cascades