The optic nerve is a tract of the diencephalon that is not completely myelinated until: (A) 5 years after bih, (B) 2 years after bih, (C) 1 year after bih, (D) 3 months after bih
Answer is D. The axons of the optic nerve are not completely myelinated until 3 months after bih. Myelinated axons are normally not found in the retina. The optic nerve is not a true peripheral nerve but a tract of the diencephalon; when severed, the optic nerve does not regenerate. Myelination in the central nervous system (CNS) is accomplished by oligodendrocytes; oligodendrocytes are not found in the retina.