substantia

Substance.

Pl. substantiae [L.] substance.

• s. alba — the white matter of the spinal cord and the brain.
• s. compacta — compact bone.
• s. gelatinosa — the substance sheathing the posterior horn of the spinal cord and lining its central canal.
• s. grisea — the gray matter of the spinal cord and brain.
• s. grisea centralis — the central gray matter that surrounds the cerebral aqueduct.
• s. nigra — the layer of gray substance separating the tegmentum of the midbrain from the crus cerebri.
• s. propria corneae — layer of transparent lamellated fibrous connective tissue which constitutes the bulk of the cornea; composed of collagen fibers disposed in platelike formations, fibroblasts and ground substance with many nerve fibers but no blood vessels.
• s. propria choroid — loose connective tissue of the choroid.