Tulane University defines an ore as a body of material from which one or more valuable substances can be extracted. For example, bauxite ore is mined and refined to extract aluminum.
root sheath the epidermic layer of a hair follicle. sheath of Schwann neurilemma. synovial sheath synovial membrane lining the cavity of a bone through which a tendon moves. tendon sheath a lubricated fibrous or synovial layer of tissue in which the tendon is housed and through which it moves.
myelin sheath. noun. The insulating envelope of myelin that surrounds the core of a nerve fiber or axon and facilitates the transmission of nerve impulses. In the peripheral nervous system, the sheath is formed from the membrane of the Schwann cell, and in the central nervous system it is formed from oligodendrocytes.