Glial Wrapping of Axons

Question

Glial wrapping of axons:
A) emerged once, prior to the vertebrate-invertebrate split.
B) reduces membrane resistance.
C) increases membrane capacitance.
D) speeds up conduction of action potentials.
E) All of the above

Accepted Answer

Glial wrapping of axons increases membrane resistance and reduces membrane capacitance in order to enable salutatory propagation to speed up action potential conduction. Although both vertebrates and invertebrates feature glial wrapping, members of the outgroup to jawed fish lack myelinated axons, and glial membrane properties are very different between invertebrate groups, strongly suggesting convergent evolution.