Gastrointestinal: Adjective referring collectively to the stomach and small and large intestines. The commonly used abbreviation for gastrointestinal is GI. (Outside of medicine, GI can also stand for galvanized iron, general issue or government issue-as in GI Joe).
Before the extracellular matrix is calcified, the tissue is called osteoid (bone-like) tissue. When the concentrations of calcium and phosphate ions rise high enough, they are deposited into the extracellular matrix, and the bone calcifies.
Bone (Osteoid and Mineralization) 1  A living tissue composed of osteoid (protein matrix) that is strengthened by the deposition of bone salts (hydroxyapatite crystals) in a process called mineralization. Hydroxyapatite: A complex of phosphate and calcium that occurs as a mineral.