Day 079 - Regeneration

Submitted by Sam on 8 August, 2011 - 08:32

Salamanders, hydra and planarian flatworms have extraordinarily adaptive regenerative capabilities, and can completely regrow amputated limbs and damaged tissues in a matter of months. Salamanders, including European newts, are unique among vertebrates in their ability to regenerate limbs, eyes, spinal cords, internal organs and their upper and lower jaws. Incredibly, newts can regenerate damaged heart muscle cells, completely repairing their heart after trauma, with no scarring of tissue. This regenerative process occurs through cellular dedifferentiation, where cells revert to an earlier developmental stage, losing their characteristic properties before replicating en masse and specializing once more to rebuild new tissue.

Some reptiles use their potent regenerative abilities as part of a self-defense system to thwart predators, where they will self-amputate part of their tail when captured, allowing them to flee the grasps of the predator and grow it back later. The detached tail will thrash around of its own accord, creating a diversion that distracts attention from the fleeing lizard, which is saved from much blood-loss through contraction of special muscles that surround the artery in its tail. This process is called autotomy, and is a survival adaptation common to octopuses, crabs, spiders and lobsters. The sea-food industry exploits the regenerative ability of autotomic stone crabs, harvesting claws from the living catch before returning them to the sea where they will regenerate within eighteen months.

With the exception of deer, who grow and shed their antlers each year, mammals have lost the ability to regenerate replica replacements for lost or damaged body parts. Regenerative medicine is the field that explores the biology of these phenomena, and holds the promise of bringing this kind of self-repairing power to humans, one day allowing us to regrow limbs, tissues and organs, simultaneously solving the problems of organ transplant rejection and instantly solving the shortage of donor organs.

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