Why does salamander grow back almost completely but lizards do not?

Differences in stem cells in the spinal cord help explain this amphibian's ability to regenerate body parts.

Both salamanders and lizards can regrow their tails, but do not achieve the same level of perfection.

While salamander tails regrow almost like the original tail, both bone and everything, the cartilage's tail is full of cartilage and lacks nerve cells. According to a report by researchers on the Proceedings of the National Academy of Sciences on August 13, this contrast is due to the difference between stem cells in the spinal cord of two species.

When a salamander loses its tail, neural stem cells in its spinal cord can develop into any form of nervous system cells, including neurons or neurons.

But co-author Thomas Lozito, a biologist from the University of Pittsburgh, said that through evolution, lizards ' nerve cells have lost this ability. When bees can regenerate cartilage and skin, lizards cannot regenerate nerve cells.

Lozito and colleagues studied neuronal stem cells (scientific name Ambystoma mexicanum) and two lizards - green lizards (Anolis carolinensis) and smooth scales (scientific name is Lepidodactylus lugubris) .

The team also wanted to know if lizard stem cells were unable to grow into nerve cells or whether anything related to the lizard's environment prevented them from growing again. So the researchers implanted neural stem cells of salamanders in the year of the gecko's tail. Some cells have become nerve cells in the tail that grows back, indicating the problem lies in the lizard's stem cells.

The finding shows that scientists will only have to replace lizard stem cells instead of other parts of the tail so they have a more complete tail.

The cross-section of the lizard's tail and salamander (left) shows cartilage (green) and nerve cells (red).In the reconstructed tail image (on the right), the lizard tail forms mainly from cartilage, while the salamander tail also develops new stem cells.(Photo from TP Lozito).

How lizards lose their ability to regenerate neurons while salamander is not a mystery. Scientists know that the position of species on the evolutionary tree is related to the ability of the organism to regenerate.

Developmental biologist Katharina Lust from the Institute of Molecular Pathology in Vienna, who was not involved in the study, said: ' The more complex species the less likely they are to reproduce their organs '. Reptile animals like lizards are more complex creatures than amphibians like salamander.

Researchers plan to use it to see if lizard's stem cells can be modified to recreate a perfect tail. Finally, the team hopes to have a day that mammalian stem cells regenerate body parts.

Lozito said: 'My goal is to create the first mouse that can reproduce its tail. We are using lizards as a stepping stone. '