Answer:
they need it to function properly
The iris controls the amount of light that enters the eye by opening and closing the pupil. The iris uses muscles to change the size of the pupil. These muscles can control the amount of light entering the eye by making the pupil larger (dilated) or smaller (constricted).
Myelinogenesis is the process by which oligodendrocytes of the central nervous system produce myelin sheath for neurons of the brain. This fatty white substance is necessary for high-speed neural transmission between nerve cells. Moreover, glial cells are the support cells of the nerve cells.
