Mark the incorrect one regarding the structures of a nerve cell ?

Options

A. Dendrites - short and branched fibres which contains receptor proteins on their surface
B. Nissl's granules - found in cyton, dendrites and axon part of neuron
C. Axon - Functional part of neuron that transmit impulses away from the cyton
D. Schwann cell - Synthesises myelin sheath around axons in spinal and cranial nerves

Answer

To solve the question regarding the incorrect statement about the structures of a nerve cell, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding the Structure of a Nerve Cell:**
- A nerve cell, or neuron, consists of several key parts: the cell body (cyton), dendrites, and axon. Each part has specific functions and characteristics.

2. **Analyzing Option A:**
- **Statement:** "Dendrites are short and branched fibers which contain receptor proteins on their surface."
- **Evaluation:** This statement is correct. Dendrites are indeed short, branched fibers that receive signals from other neurons and contain receptor proteins that facilitate this process.

3. **Analyzing Option B:**
- **Statement:** "Nissl granules are found in cyton, dendrites, and axon part of neuron."
- **Evaluation:** This statement is incorrect. Nissl granules, which are composed of rough endoplasmic reticulum and ribosomes, are primarily found in the cell body (cyton) and dendrites, but they are absent in the axon. Therefore, this option is the incorrect one.

4. **Analyzing Option C:**
- **Statement:** "Axon is the functional part of neuron that transmits impulse away from the cyton."
- **Evaluation:** This statement is correct. The axon is responsible for transmitting impulses away from the cell body to other neurons or muscles.

5. **Analyzing Option D:**
- **Statement:** "Schwann cell synthesizes myelin sheath around axon spinal and cranial nerve."
- **Evaluation:** This statement is also correct. Schwann cells are responsible for producing the myelin sheath that insulates axons in the peripheral nervous system.

6. **Conclusion:**
- The incorrect statement regarding the structures of a nerve cell is **Option B**.

### Final Answer:
**Option B** is the incorrect statement regarding the structures of a nerve cell.