Question

Do brain cells undergo mitosis? What about neurons?

Answer 1

Hint: The brain is the central part of the total nervous system. It is the seat for processing and neural coordination. The nervous system is categorically divided into two main types- The central nervous system and the Peripheral nervous system.
The central nervous system comprises the brain and spinal cord. The brain is actually a bundle of nerve fibers brought together which get modified in the embryonic stages to get converted into specialized regions in the brain and are able to perform special tasks and coordinate among themselves to control various functions of the body.

Complete answer:
As discussed, the brain is actually made up of neurons. The neurons are held together by connective tissues. Apart from this, some specialized epithelial cells like the ependymal cells are there which perform some sort of secretory activities. The ependymal cells secrete the cerebrospinal fluid (CSF) in the brain ventricles and help the regions of the brain supply nutrients and eliminate the waste product.
While these connective tissue cells and epithelial cells can undergo mitosis and regenerate themselves upon damage or to replace the older ones, the main brain cells or the neurons cannot undergo mitosis. Their number remains the same from birth. If these neurons are damaged, then they never get repaired, and this may give rise to various coordinating problems/diseases/disorders in the body like paralysis, lack of control of autonomous functions, etc.
The neurons can only divide in their embryonic stage. Upon birth, they lose this ability to divide permanently.

Note:
One may wonder why the neurons lose their ability to divide. Well, this query may be answered with respect to cell division. We all should be familiar with the phases of the cell cycle, i.e., the G1 phase, S phase, G2 phase, and the M phase.
There is another phase where the cell division cycle stops temporarily for an unknown period of time called the G0 phase. The G0 phase comes after the G1 phase. Some of the cells enter this phase after the G1 phase and here the cells stop their cell division cycle.
The duration for which the cells may remain in G0 phase is undefined. Many cells overcome this G0 phase whereas others may never overcome it.