How do lizards regrow limbs

Did you know that there are some living things that regenerate parts of their body? Humans can't, but some creatures can re-grow their limbs or tails or even their brains!

Sometimes, animals even cast off a part of their body on purpose. They might feel threatened, and they can re-grow it later — this is called autotomy. The axolotl say "ax-oh-lot-el" is a Mexican species of salamander. It's also known as a Mexican walking fish. It can regenerate, repair or replace its arms, legs, tail, lower jaw, brain and heart.

What an awesome ability! Scientists are very interested in studying how the axolotl is able to do this. They are able to grow back all of their limbs if they lose any from an attack. They can also drop or release an arm when predators grab them. They found that at least genes in specific spots along each tail were "turned on" during regeneration -- suggesting that lizard DNA has a genetic "recipe" for regeneration.

Instead, the cells are dividing in distinct pockets including muscle, cartilage, spinal cord, and skin all throughout the tail. Story continues below The regenerated lizard tails.

The green anole lizard Anolis carolinensis , when caught by a predator, can lose its tail and then grow it back. Researchers have discovered the genetic 'recipe' that explains how this happens.

What about human limb regeneration? The researchers said their finding may help pave the way for new therapeutic approaches for birth defects and spinal cord injuries -- and possibly arthritis too. The axolotl is easy to breed in captivity, which has made it the focus of intensive research.

When it loses a limb, cells migrate to the site of the wound, turning back their internal clocks on the way. The cells form a blastema, a mass of undifferentiated cells, like embryonic cells or stem cells.

Immune cells called M2 macrophages reduce inflammation at the wound site, while connective tissue cells called fibroblasts carry positional information that allows them to differentiate into the appropriate specialised cells specific to their location as the lost limb regrows. Scientists have recently mapped the axolotl genome and this should speed up our genetic understanding of why some creatures can regenerate their limbs.

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