Final answer:
To regain function and feeling in his toe, myelin and the neurilemma play critical roles in nerve impulse transmission and nerve repair by providing insulation and support for nerve regeneration, which are essential for the recovery of severed nerves.
Step-by-step explanation:
Juan's ability to regain function and feeling in his toe after it was sewn back on involves complex neural repair mechanisms. While several components of the neuron and surrounding cells contribute to nerve function, the myelin sheath is particularly important for efficient nerve impulse transmission.
Myelin is a fatty substance formed by glial cells such as Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. It insulates axons to ensure rapid and efficient transmission of electrical signals. This is crucial for Juan's toe functionality because the myelinated nerves are involved in relaying sensations and controlling muscle movements. The restoration of the myelin sheath around the severed nerves is key to enabling them to function properly.
Furthermore, the neurilemma, which is the outermost layer of the Schwann cells that contribute to nerve fiber regeneration in the peripheral nervous system, also plays a role in recovery after an injury. The neurolemma supports nerve regeneration by forming a regeneration tube that guides the regrowth of the axon.
In summary, while dendrites are the structures that receive signals, and the process of remyelination is essential during nerve repair, the final answer is that myelin and the neurilemma are most directly responsible for Juan's regained function and feeling. They work together to ensure that nerve impulses can once again travel efficiently through the damaged nerve to communicate with the brain and other parts of the body.