medulla

nouns

a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers
lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata)
"the medulla oblongata is the most vital part of the brain because it contains centers controlling breathing and heart functioning"
is derived from
the inner part of an organ or structure in plant or animal
is derived from
antonym
is a type of (narrower)
the tissue in the bodies of animals
is a type of (narrower)
the tissue of a plant