medullary

Med"ul*la*ry, a. Etym: [L. medullaris, fr. medulla marrow: cf. F. médullaire.] 1. (Anat.) (a) Pertaining to, consisting of, or resembling, marrow or medulla. (b) Pertaining to the medula oblongata. 2. (Bot.) Defn: Filled with spongy pith; pithy. 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.

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