Directed Blast

Axolotls (Ambystoma mexicanum) fascinate scientists with their ability to regenerate after injury. A gene called Shh helps to define the pattern of a regrowing limb, first during development then after injury. But it’s not just Shh that shapes the mass of regenerating cells, or blastema. To develop correctly, cells on different sides of the blastema need to communicate to orientate the new limb’s growth. In these slices through axolotl limbs, we see normal asymmetric patterns of muscle (stained red) and cartilage (blue) in a normal limb (lower left) and a regenerated limb (top left) grown from a blastema with intact connections between cells on the top (dorsal) and lower (ventral) sides. When these connections are disrupted (right), regenerating limbs develop more symmetrically. Investigating this relationship between orientation and genetics might guide future approaches to regenerative medicine in humans.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image from work by Sakiya Yamamoto and colleagues
• Okayama University, Graduate School of Environmental, Life, Natural Science and Technology, Okayama, Japan
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in eLife, February 2026