This is fucking cool.
I've been reading about the MRL mouse, a lab-bred strain which has been discovered to have an unusual property: amazing powers of regeneration. They weren't bred for that, though; instead, they were selected for large size, and were then discovered to have a defect in the cell death gene fas, which made them a useful model for autoimmune research—they had excessive proliferation of lymphatic cells.Whoa indeed.
One way to mark individual mice is by punching small holes in their ears (it sounds cruel, I know…fathers with teenage daughters also think it is a terrible thing to do). The mice of the MRL strain do something remarkable, though, as you can see to the right: they heal right up. There is no detectable scar tissue, either—these mice regenerate.
Regrowing ears might be a very big deal to a mouse, but not so much to us. However, their powers of regeneration go deeper. Damage their livers, their kidneys, and many other tissues, and they grow right back. They can regrow lopped off toes and tails. Here's the big one: take a fine wire, stick it in their heart, and burn a hole in it with extreme cold, a process called cryo-damage which mimics the damage of a myocardial infarction, and in the MRL mouse, heart tissue regenerates.
Atrios channeling Kent Brockman: "I, for one, will welcome our mutant mice overlords."