What is the white and gray matter in the brain really made of?

Question

Hi, I'm really interested in neurology and neuroanatomy and I was confused about white and gray matter in the brain. White matter is myelinated axons and gray matter is somas, but doesn't each neuron have one soma and one axon? Do some neurons within the brain not have axons? Do some have multiple axons?

Hi, I'm really interested in neurology and neuroanatomy and I'm confused about white and gray matter in the brain and spinal cord. White matter is myelinated axons and gray matter is somas, but doesn't each neuron have one axon and one soma? Do some neurons not have axons? Do some not have multiple axons? Do some not have somas?

Answer 1

All typical neurons have a soma and an axon. Some have branched axons. The difference between gray matter and white matter is that, as you point out, white matter is the part of the brain that contains the myelnated axons, i.e axons that are covered by the myelin sheath. There are other axons that are unmyelnated, and this comprises the gray matter. It isn't correct to say that gray matter is somas, because soma is the cell body of the neuron, and all axons have that.