root sheath
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:
- root sheath
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1. An epithelial extension of the cervical loop of the enamel organ, consisting of the inner and outer enamel epithelium, and directing the number and morphological growth of the roots. It is bordered externally by the dental sac and internally by developing cementum and root dentin, and ultimately becomes the epithelial diaphragm. Called also "Hertwig's sheath" and "sheath of Hertwig."
2. The epithelial portion of the hair follicle, divided into the inner root sheath and the outer root sheath, which gives rise to the sebaceous glands.
Used in 4 Term definitions
Used in 4 Term definitions