Assertion [A] : Nerve cells cannot be regenerated.
Reason [R] : Nerve cells lack centrioles.
Assertion [A] is True and Reason [R] is True and sufficiently explains [A].
Nervous tissue is derived from ectoderm .It is highly sensitive which can receive and propagate any changes in the surroundings.This tissue has a very least regenarating power as they dont have centrioles.It consumes for about 20 % of energy and 80% of oxygen of an organism.
A typical Neuron it has a head like part called cell body and a conducting shaft called Axon the cell body is similar to other types of cells. It has a nucleus with at least one nucleolus and contains many of the typical cytoplasmic organelles. It lacks centrioles, however. Because centrioles function in cell division, the fact that neurons lack these organelles is consistent with the amitotic nature of the cell.