Nissl's granules are characteristically found in

The cell body of a neuron contains:

Choose the correct statements about Nissl's granules from the codes given below:
$I.$ There are regular masses of ribosomes
$II.$ There are irregular masses of ribosomes and $ER$
$III.$ There are granular bodies
$IV.$ They synthesise proteins in the cell

What is the myelin sheath derived from?

Non-excitable cells,found among the neurons are called

Which of the following statements is correct regarding the $Nodes$ of $Ranvier$?