What connective tissue layer surrounds an axon?Multiple ChoiceEndoneuriumPerineuriumMyelin sheathEpineurium

Step 1: Understanding the Connective Tissue Layers

Connective tissue in the nervous system provides support and protection to nerve fibers (axons). There are several layers of connective tissue that surround axons and nerves.

Step 2: Identifying Each Option

1. Endoneurium: This is a delicate layer of connective tissue that surrounds each individual axon.
2. Perineurium: This layer surrounds a group of axons, forming a fascicle.
3. Myelin sheath: This is not a connective tissue layer but rather a lipid-rich covering formed by Schwann cells that insulates the axon.
4. Epineurium: This is the outermost layer that surrounds the entire nerve, including all the fascicles and blood vessels.

Step 3: Analysis of Options

From the definitions:

• The Endoneurium is the most closely associated with the axon itself as it encloses individual axons.
• The Epineurium and Perineurium cover larger structures but are not specific to individual axons.

Step 4: Conclusion

The layer that specifically surrounds an axon is the Endoneurium.

Final Answer

Endoneurium is the connective tissue layer that surrounds an axon.