Nissl's granules are present in which part of a neuron?

Identify $X$ and $Y$ in the given figure.

In the following list,how many structures are included in grey matter?
Cell body,myelinated axon,unmyelinated axon,and dendron.

What do neurons lack?

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:

What is the structural and functional unit of the neural system?