Question

What is the evidence that supports this statement: Limb regeneration is always in the distal direction.

Answer 1

Regeneration always proceeds in a direction distal to the cut surface.

When the limb is amputated then it will re-establish blood supply when fused to the trunk. The cells in and near the cut limb dedifferentiate to form a mass of stemlike cells that can produce all the specialized tissue of limb such as muscle, blood vessels and nerves.

The evidence we get is seen in "Salamander". When the limb is cut then it will regenerate from proximal to distal.

First after the limb is cut then there is wound healing.

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Blastema formation.

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Blastema cell proliferation.

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Patterning new limb tissue.

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Newly generated limb.

Also we can see in hydra that when it gets cut then the limb regenerate from proximal to distal end.

So, from these we can get evidence that limb regeneration is from proximal to distal direction.

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