Which type of neurons are most abundant in the human body?

The cells lining the ventricles of the brain and the central canal of the spinal cord are known as:

Nissl's granules are found in the cyton of nerve cells. These have an affinity for basic dyes. The granules are made up of:

Synaptic knob is a bulb-like structure which is present:

Which of the following statements are correct?
$I$. Dendrites are long fibres with branched distal ends.
$II$. Axons are short fibres which arise from the cell body.
$III$. The cell body of a neuron contains cytoplasm,a nucleus with cell organelles,and Nissl's granules.
$IV$. Dendrites transmit nerve impulses away from the cell body to a synapse.
The correct option is:

Schwann cells are found around: