Like heart muscle cells, neurons no longer divide after differentiation.
That way, if they are destroyed, they are no longer replaced. However, neuron extensions can, within certain limits, regenerate as long as the cell body has not been destroyed.
When an axon is accidentally cut, which occurs in the case of skin wounds, the region that is attached to the cell body is called the proximal stump, and the area that is separated is called the distal stump. The latter degenerates and is phagocytized by macrophages, which clear the injured region. Already the nearby stump grows and branches. At the same time, cells that make up the myelin sheath of the distal stump change and proliferate, resulting in cell columns that will guide the branches growing from the proximal stump. When one of these branches penetrates this column of cells, it completely regenerates the axon.
When the space between the proximal and distal stump is too large or when an amputation occurs, the branches of the proximal stump grow disorderly, intertwine, and form a very pain-sensitive structure called the amputation neuroma.