Which of the following statement is true ?

Options

A. Saltatory conduction is seen in non-myelinated nerve fibres
B. Nissl's granules are found in muscles fibres
C. Non-myelinated nerve fibres do not possess nodes of Ranvier
D. Non-myelinated nerve fibres are completely enclosed by a myelin sheath

Answer

To determine which statement is true among the given options, let's analyze each statement step by step.

### Step 1: Analyze the First Statement
**Statement:** "Solitary conduction is seen in non-myelinated nerve fibre."

- **Explanation:** Solitary conduction refers to the process of action potential propagation in myelinated nerve fibers, where the action potential jumps from one node of Ranvier to another. In non-myelinated fibers, the action potential propagates continuously along the entire length of the fiber. Therefore, this statement is **false**.

### Step 2: Analyze the Second Statement
**Statement:** "Nasal granules are found in Muscle Fibre."

- **Explanation:** Nasal granules, also known as Nissl bodies, are found in neurons, not muscle fibers. They consist of rough endoplasmic reticulum and ribosomes, which are involved in protein synthesis. Therefore, this statement is **false**.

### Step 3: Analyze the Third Statement
**Statement:** "Non-myelinated nerve fibres do not possess nodes of Ranvier."

- **Explanation:** Nodes of Ranvier are gaps in the myelin sheath that are present in myelinated nerve fibers. Non-myelinated nerve fibers do not have a myelin sheath at all, and thus they do not have nodes of Ranvier. Therefore, this statement is **true**.

### Step 4: Analyze the Fourth Statement
**Statement:** "Non-myelinated nerve fibers are completely enclosed by a myelin sheath."

- **Explanation:** This statement is contradictory because non-myelinated nerve fibers, by definition, do not have a myelin sheath. Therefore, this statement is **false**.

### Conclusion
The only true statement among the options provided is the third statement: "Non-myelinated nerve fibres do not possess nodes of Ranvier."

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