root sheath

root sheath
root sheath n the epidermal lining of a hair follicle

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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. and s. of Hertwig. 2. the epithelial portion of the hair follicle, divided into the inner root sheath and the outer root sheath. The inner root sheath has three layers: Huxley layer, Henle layer, and the cuticle of the root sheath. The outer root sheath does not have distinct layers and merges with the epidermis near the skin surface.

Medical dictionary. 2011.

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  • root sheath — noun 1. a. : a many layered epidermal sheath surrounding an aerial root (as the velamen in an epiphytic orchid) b. : coleorhiza 2. : the epidermal lining of a hair follicle comprising two principal layers of cells that make up an inner and an… …   Useful english dictionary

  • Root sheath — Infobox Anatomy Name = PAGENAME Latin = GraySubject = 234 GrayPage = 1068 Caption = Transverse section of hair follicle. Caption2 = Precursor = System = Artery = Vein = Nerve = Lymph = MeshName = MeshNumber = DorlandsPre = s 10 DorlandsSuf =… …   Wikipedia

  • Hertwig's epithelial root sheath — The Hertwig s epithelial root sheath (frequently abbreviated as HERS ) is a proliferation of epithelial cells located at the cervical loop of the enamel organ in a developing tooth. Hertwig s epithelial root sheath initates the formation of… …   Wikipedia

  • Outer root sheath — The outer root sheath of the hair follicle encloses the inner root sheath and hair shaft.[1] It is continuous with the basal layer of the interfollicular epidermis (skin). References ^ James, William; Berger, Timothy; Elston, Dirk (2005) Andrews… …   Wikipedia

  • cuticle of root sheath — the innermost layer of cells of the inner root sheath of a hair follicle adjacent to the hair …   Medical dictionary

  • sheath — I (New American Roget s College Thesaurus) n. scabbard, sheathing, case, envelope, casing; involucre, capsule, fascia, lorica. See covering, receptacle. II (Roget s IV) n. Syn. case, scabbard, cover, spathe, sheathing, cere. Specialized sheaths… …   English dictionary for students

  • sheath of Hertwig — sheath of Hert·wig hert .vig n a two layered epithelial wall that covers the developing root of a tooth, is derived from cells of the enamel organ, and later breaks up during the process of cement deposition called also Hertwig s sheath Hert·wig… …   Medical dictionary

  • sheath — O.E. sceað, scæð, from P.Gmc. *skaithiz (Cf. O.S. scethia, O.N. skeiðir (pl.), O.Fris. skethe, M.Du. schede, Du. schede, O.H.G. skaida, Ger. scheide scabbard ), possibly from root *skaith divide, split (see SHED (Cf …   Etymology dictionary

  • sheath — 1. Any enveloping structure, such as the membranous covering of a muscle, nerve, or blood vessel. Any sheathlike structure. SYN: vagina (1). 2. The prepuce of male animals, especially of the horse. 3. A specially designed tu …   Medical dictionary

  • Root of penis — Infobox Anatomy Name = PAGENAME Latin = radix penis GraySubject = 262 GrayPage = 1249 Caption = The constituent cavernous cylinders of the penis. Caption2 = Vertical section of bladder, penis, and urethra. Precursor = System = Artery = Vein =… …   Wikipedia

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