Nissl’s granules are found in

The correct answer is Nerve cells.

Let us understand the structure and function of Nissl's granules step-by-step to see why they are specifically found in nerve cells (neurons):

1. What are Nissl's granules?
Nissl's granules (also known as Nissl bodies) are large granular structures found within the cytoplasm of neurons. Chemically, they are composed of rough endoplasmic reticulum (RER) with numerous free ribosomes. The presence of ribosomes gives them a high concentration of RNA, making them highly basophilic (staining darkly with basic dyes like methylene blue or cresyl violet).

2. Where are they located in a nerve cell?
Nerve cells consist of three main parts: the cell body (cyton or soma), dendrites, and an axon. Nissl's granules are abundantly present in the cell body (soma) and the dendrites. However, they are completely absent in the axon and the axon hillock (the region where the axon connects to the cell body).

3. What is their function?
Because they are rich in ribosomes and rough endoplasmic reticulum, the primary function of Nissl's granules is protein synthesis. Neurons require a massive amount of proteins and neurotransmitters to transmit nerve impulses and maintain their structure, and these granules act as the primary protein-manufacturing hubs of the nerve cell.

4. Why are they not found in the other options?

• RBCs (Red Blood Cells): Mature mammalian RBCs lack a nucleus, endoplasmic reticulum, and ribosomes entirely to maximize space for hemoglobin, so they cannot have Nissl's granules.
• WBCs (White Blood Cells) and Platelets: While WBCs have standard organelles and platelets are cell fragments, they do not contain these specialized, highly concentrated basophilic RER-ribosome complexes (Nissl's granules), which are unique features characterizing neurons.