If you want to know interesting things that you may not have learned yet, Delanceyplace is a good place to go. From a story by Michaeleen Doucleff about children regenerating fingertips:

“‘When I was three years old I caught my thumb in a folding chair. I cannot remember this episode, filled as it must have been with blood and pain, but my mother does. She packed the amputated tip of the thumb on ice and rushed me to the Emergency Department, where a surgeon sewed it back on again. I still have the scar on my thumb now, running parallel to the base of my nail.

‘What my mother didn’t know, and what most doctors still don’t, is that my thumb would almost certainly have grown back perfectly without any treatment. It would have regenerated in the same way as some amphibians can grow back their tails or legs. Bone, nail, nerves, blood vessels, the whole lot. All it needed was a gentle clean, a non-adherent dressing, and a lollipop to soothe my frayed, three-year-old nerves.

‘It turns out humans can regenerate, but only the very tips of their fingers and only [some] children. In the 1970s a Sheffield paediatrician even published a paper on this effect in the Journal of Paediatric Surgery. Her results were unequivocal: amputations above the last joint in children under six left to heal naturally would regrow, the entire finger, without a scar or deformity!'”

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Not regeneration but transplantation, 2011: