Marrow

The bone marrow.

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1. A highly cellular hematopoietic connective tissue filling the medullary cavities and spongy epiphyses of bones; it becomes predominantly fatty with age, particularly in the long bones of the limbs. 2. Any soft gelatinous or fatty material resembling the m. of bone. SEE ALSO: medulla. [A.S. mearh]

- bone m. [TA] the soft, pulpy tissue filling the medullary cavities of bones, having a stroma of reticular fibers and cells; it differs in consistency by age and location. SEE ALSO: gelatinous bone m., red bone m., yellow bone m.. SYN: medulla ossium [TA].

- gelatinous bone m. [TA] degenerated m. of cranial bones in old age.

- red bone m. [TA] bone m. in which the stroma primarily contain the developmental stages of erythrocytes, leukocytes, and megakaryocytes; it is present throughout the skeleton during fetal life and at birth. After the fifth postnatal year, it is gradually replaced in the long bones by yellow m.. SYN: medulla ossium rubra [TA].

- spinal m. SYN: spinal cord.

- yellow bone m. [TA] bone m. in which the stroma of the reticular network are largely filled primarily with fat; it replaces red m. in the long bones after the fifth year of life. SYN: medulla ossium flava [TA].

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mar·row 'mar-(.)ō, -ə(-w) n

1) BONE MARROW

2) the substance of the spinal cord

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n.

see bone marrow

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mar·row (marґo) 1. medulla ossium. 2. any of various soft substances resembling bone marrow (medulla ossium).