Mammals - Regeneration in Vertebrates
Mammals are not capable of regenerating limb or tails. However, there are a few exceptions where lost tissues are regenerated. The annual replacement of antlers in dm is ones such instance. The old antlers are shed, and new ones grow to replace them. It has been observed that in the infant opossums (marsupial) that are rather incompletely differentiated at birth, amputated hind limbs possess extensive ability for regeneration. A cut hind limb regenerates while stimulated by implantation of a fragment of brain into it. Generally, however, regenerative capability in mammals is limited only to tissue regeneration, such as wound healing, repair of bone fractures and damaged muscles. Mammals possess extensive power to regenerate liver later than more than 75% of it is removed. However, the lost part of the liver are not restored. The residual part of liver increases in size through cell division to restore the original size of the organ. This is an example of compensatory hypertrophy.
So far there is no proof to show that major limb parts in mammals regenerate, though amputation by the terminal phalanges of hands in human children can be followed by whole regeneration of the finger tip. The full length of the finger may be restored and the nail and finger print whoole appear normal. There is normally no loss of mobility or sensation. Regeneration in these instances however occurs only in nonexistence of surgical intervention. Some researchers have pointed out electrical currents as being helpful in regenerating finger tips in humans.