The baldness follows a specific pattern, more so in men. Even in advanced cases of baldness, it is rare for most men to lose the area in back and sides of the scalp (horseshoe hair bearing area). This is because the hair in these areas are genetically said to be resistant to the balding effect of male hormone i.e. they will remain unaffected permanently. This is called donor dominance (the term was introduced by Orentriech in 1959).
Donor dominance means the hairs retain the characteristic feature of being resistant to the balding effect of male hormones even after they have been transplanted to the new (recipient) site. In other words the transplanted hairs stay permanent.
Hair transplant has become now valid and established procedure due to this trait of hair, giving permanent and natural results.