Answer:
see the answer below
Step-by-step explanation:
The cells of the brain and spinal cord are irreplaceable because these cells do not undergo cell divisions like some other cells of the body.
Through cell division of the vegetative cells, damaged cells of the body are replaced by new cells. The cells of the brain and spinal cords however are special cells that will not divide under ordinary conditions. Hence, when there is any form of damage, there are no new cells to replace the damaged cells.