Why can't neurons undergo cell division?
Morphological point of view

Neurons cannot divide because they lack centrioles.


  Because centrioles function in cell division, the fact that neurons lack these organelles is consistent with the amitotic nature of the cell [1].


Functional point of view

New cells in the nervous system wouldn't do any good. The whole nervous system is based on interneuronal connections, so adding an extra neuron would mess up these connections and alter both the functionality and the "stored" information.


  Each nerve cell has a specific place in our nervous system. Its job is all about taking a signal from one specific place to another one. Adding new nerve cells would mess up these very specific connections in a very complex system [2].




References:


SEER Training. NERVE TISSUE. Available from http://training.seer.cancer.gov/anatomy/nervous/tissue.html
UCSB Science Line. Available from http://scienceline.ucsb.edu/getkey.php?key=1710