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.
(March 2011) In histology, osteoid is the unmineralized, organic portion of the bone matrix that forms prior to the maturation of bone tissue. Osteoblasts begin the process of forming bone tissue by secreting the osteoid as several specific proteins. When the osteoid becomes mineralized, it and the adjacent bone cells have developed into new bone tissue. Osteoid makes up about fifty percent of bone volume and forty percent of bone weight. It is composed of fibers and ground substance. The predominant fiber-type is Type I collagen and comprises ninety percent of the osteoid.