Botany. a narrow zone made up of the innermost layer of woody tissue immediately surrounding the pith in plants.
(anatomy) a myelin layer surrounding and insulating certain nerve fibres
a layer of thick-walled cells surrounding the pith of the stems of some higher plants
medullary sheath n.
See myelin sheath.
- Medullary sponge kidney
medullary sponge kidney n. A cystic disease of the renal pyramids characterized by calculus formation and hematuria but usually not with renal failure.
- Medullary space
medullary space n. The marrow-filled central cavity together with the cellular intervals between the trabeculae of bone.
- Medullary stria of fourth ventricle
medullary stria of fourth ventricle n. Any of the slender fascicles of fibers extending transversely below the ependymal floor of the ventricle from the median sulcus to enter the inferior cerebellar peduncle. Also called acoustic stria.
- Medullary stria of thalamus
medullary stria of thalamus n. A narrow compact bundle of fibers extending along the line of attachment of the roof of the third ventricle to the thalamus on each side and terminating posteriorly in the habenular nucleus.