The Question:

Do nerves grow out from within or in from the skin?


My guess is outwards.

However, I have a vague memory of a study involving frogs that I read about in a pop science book - I forgot which - that took skin from the back & chest of a bunch of frogs, swapped them, then tested their reactions. If I remember correctly, some of the frogs wiped their chest when the skin on their back was stimulated (and/or vice versa). That would suggest that they grow inward from the skin.

Some vaguely formed hypotheses:

  1. Nerves grow inwards from skin.
  2. Nerves grow outwards from, say, the brain.
  3. Some combination of 1. and 2.


I have no formal training in biology. I read a handful of textbooks on evolution for fun though, like "99% Ape", "Why Evolution is True", and some of Dawkins' work, including "The Selfish Gene".



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