Medullary groove (Anat.), a groove, in the epiblast of the vertebrate
blastoderm, the edges of which unite, making a tube (the medullary
canal) from which the brain and spinal cord are developed. -- Medullary
rays (Bot.), the rays of cellular tissue seen in a transverse section
of exogenous wood, which pass from the pith to the bark. -- Medullary
sheath (Anat.), the layer of white semifluid substance (myelin),
between the primitive sheath and axis cylinder of a medullated nerve
fiber.
Me*dul"la*ted (?), a. (Anat.) Furnished with a medulla or marrow, or
with a medullary sheath; as, a medullated nerve fiber.
Me*dul"lin (?), n. [Cf. F. médulline.] (Bot. Chem.) A variety of lignin
or cellulose found in the medulla, or pith, of certain plants. Cf.
Lignin, and Cellulose.
||Me*du"sa (?), n. [L., fr. Gr. &?;.] 1. (Class. Myth.) The Gorgon; or
||one of the Gorgons whose hair was changed into serpents, after which
||all who looked upon her were turned into stone.