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The sheath is also responsible for multiple or accessory roots (medial growth) and lateral or accessory canals in the root (break in epithelium). [3] It is controversial, but HERS may be involved in cementogenesis and the secreting of cementum, or that HERS-derived products might be related to enamel-related molecules, and that these proteins might initiate acellular cementum formation.
Acellular cementum forms first. The cementoblasts differentiate from follicular cells, which can only reach the surface of the tooth's root once Hertwig's Epithelial Root Sheath (HERS) has begun to deteriorate. The cementoblasts secrete fine collagen fibrils along the root surface at right angles before migrating away from the tooth.
The sheath is irregularly fragmented in time and space as it promotes cementum deposition on the newly formed dentin. After this fragmentation, Hertwig's epithelial root sheath also participates in cementogenesis and formation of the periodontal ligament, giving rise to the epithelial rests of Malassez
Tooth development begins at week 6 in utero, in the oral epithelium. The process is divided into three stages: Initiation; Morphogenesis and; Histogenesis [2]; At the end of week 7 i.u., localised proliferations of cells in the dental laminae form round and oval swellings known as tooth buds, which will eventually develop into mesenchymal cells and surround the enamel organ.
In dentistry, the epithelial cell rests of Malassez (ERM) or epithelial rests of Malassez (pax epithelialis pediodontii) are part of the periodontal ligament cells around a tooth. They are discrete clusters of residual cells from Hertwig's epithelial root sheath (HERS) that didn't completely disappear.
Root sheath may refer to any of these biological structures: Epithelial root sheath, a proliferation of epithelial cells located at the cervical loop of the enamel organ in a developing tooth; Root sheath (hair), at the base of a hair follicle Inner root sheath; Outer root sheath; Seed root sheath, root sheaths in the seeds of plants
During this stage of odontogenesis, the epithelial tooth germ forms a bell-shaped structure in the labio-lingual section and is characterised by the formation of the dental sac. The peripheral cells of the dental papilla undergo differentiation, growing larger in size and taking a columnar (uni-layered) form and are now referred to as ...
The dental lamina is a band of epithelial tissue seen in histologic sections of a developing tooth. [1] [2] The dental lamina is first evidence of tooth development and begins (in humans) at the sixth week in utero or three weeks after the rupture of the buccopharyngeal membrane. It is formed when cells of the oral ectoderm proliferate faster ...