This shows what normal discs
look like in the lower back.
The central part has a significant amount of water within it and behaves something like jello or like an expensive gel-filled
This inner part of the disc, the nucleus, is a bright gray on these pictures.
The outer part of the disc, the annulus, is a tough, fibrous layer that is strong. It keeps the softer nucleus in place. It is dark on these pictures and looks the same as the edges of the bone.
The inner part of the bone, the bone marrow, contains cells that produce red and white blood cells.