Hertwig epithelial sheath

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Histological sections of the tooth development stages. hers stands for hertwig's epithelial root sheath , the Hertwig epithelial sheath, erm stands for epithelial cell rests of malassez , the Malassez epithelial remains.
Schematic representation of the Hertwig epithelial sheath: (1) HES, (2) MER,
(3) dental follicles, (4) cementoblasts,
(5) periodontal ligament, (6) alveolar cells, (7) bones, (8) odontoblasts.

Hertwig epithelial sheath (HES, also Hertwig's epithelial sheath , epithelial root sheath or vagina radicis epithelialis ) is the name given to the area of ​​the folds between the inner and outer enamel epithelium of the tooth enamel organ (Organon enameleum). It was named after its discoverer Oscar Hertwig , who discovered it in amphibians in 1874 .

The Hertwig epithelial sheath is part of tooth development and is used for root formation, which only takes place when the formation of the tooth crown with its hard substance, the tooth enamel , is largely complete. In the area of ​​the envelope fold between the inner and outer enamel epithelium, no enamel is produced, but the two sheets lie close to one another. Through proliferation , the enamel organ grows deeper in this area and preforms the attachment of the later tooth root by partially growing the edges towards one another. The transition from the outer to the inner sheet of the enamel organ is elongated and forms one, two or three root canals . The Hertwig epithelial sheath becomes increasingly patchy from the cervical point of view. The mesenchymal cells of the tooth sac (tooth follicle) come into contact with the root dentine and form the root cement and the periodontal membrane .

Malassez epithelial remains

Remnants of the Hertwig epithelial sheath remaining after the tooth-supporting apparatus has formed are referred to as Malassez epithelial remains (MER, also Malassez epithelial islands according to Louis-Charles Malassez ). He called her Débris épithéliaux . They remain in the periodontal membrane that forms from the tooth sac and, in inflammatory processes, are causally involved in the formation of radicular cysts in the jaw area, as the epithelia fuse and centrally necrotize . They are closely related to mechanoreceptors and free nerve endings and contain neuropeptides such as calcitonin gene-related peptides (CGRP) and substance P (SP).

Malformation

A disturbed development can lead to taurodontia .

Individual evidence

  1. ^ X. Luan, Y. Ito, TG Diekwisch: Evolution and development of Hertwig's epithelial root sheath. In: Developmental Dynamics . Volume 235, Number 5, May 2006, pp. 1167-1180, ISSN  1058-8388 . doi: 10.1002 / dvdy.20674 . PMID 16450392 . PMC 2734338 (free full text). (Review).
  2. ↑ O. Hertwig: About the tooth system of the amphibians and its importance for the genesis of the skeleton of the oral cavity. In: Arch. Mikrosk. Anat. DevMech. 11 (suppl), 1847, pp. 55-56.
  3. ↑ R. Lüllmann-Rauch: pocket textbook histology: 10 tables . Georg Thieme Verlag, 2006, ISBN 3-13-129242-3 , p. 353–.
  4. ↑ G. Klöppel, P. Rudolph, Th Mentzel: Pathology . Springer, 2009, ISBN 978-3-540-72884-9 , p. 126–.
  5. ↑ J. Barth: Anatomy: special biology of the masticatory system . Verlag Neuer Merkur, 1992, ISBN 3-921280-84-2 , p. 61–.
  6. ↑ KJ Heyeraas, I. Kvinnsland u. a .: Nerve fibers immunoreactive to protein gene product 9.5, calcitonin gene-related peptide, substance P, and neuropeptide Y in the dental pulp, periodontal ligament, and gingiva in cats. In: Acta odontologica Scandinavica. Volume 51, Number 4, August 1993, pp. 207-221, ISSN  0001-6357 . PMID 7694439 .

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