The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.

DEFINITION:

collagen fibrils

Delicate fibrils of collagen in connective tissue, composed of molecules of tropocollagen in linear arrays. In Type I collagen, the most common type, the tropocollagen molecules are associated in periodic, staggered arrays that give the appearance of cross-banding, with a period of approximately 65 nm in the unit fibril (or microfibril); these unit fibrils are aggregated in bundles to form larger fibrils, with longitudinal striations, which may themselves be aggregated into fibers. Some other types of collagen also associate into fibrils (e.g., Types II, III, VI) but may not aggregate to show cross-banding or to form fibers. The terms fiber and fibril are sometimes interchanged loosely in descriptions of the hierarchy of collagen aggregation.