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Histo exam 2 terms
Histology
| Question | Answer |
|---|---|
| cervical loope | growing free border of the enamel organ. here the outer and inner enamel epithelial cell layers are continuous with each other. |
| epithelial deaphragm | formed by the root sheath at the begining of root development, important during root formation. narrows the width of the cervical opening of the root. |
| root sheath | merged outer and inner epithelial layers of the enamel organ extending beyond the region of the crown to invest the developing root. |
| periodontal ligament | connective tissue ligament that is a mode of attachment of the tooth to the alveolus and that consists of collagenous fiber bundles. between the bundles are loose connective tissue, blood vessels, and nerves. |
| epithelial rests | origin from the epithelial root sheath that covers the roots during root development. as the sheath develops further, it breaks up into epithelial cell rests, which migrate into the periodontal ligament. occasionally they may develp into dental cysts. |
| resting, degenerating, proliferating | Epithelial rest cell groups: |
| alveolar bone | ridge of bone; refers to tooth-bearing part of the mandible and maxilla because it contains the tooth sockets. |
| reduced enamel epithelium | the layers of the epithelial enamel organ compacted and remaining on the surface of enamel after its formation is complete. |
| osteoblasts | bone forming cells derived from mesenchyme. they form the osseous matrix, in which they may become enclosed to become osteocytes. |
| osteocytes | cells of the bone located within lacunae, functioning in maintenance and vitality of bone. |
| osteoclasts | multinucleated cells larger than osteoblasts and derived from monocytes from the bloodstream. osteoclasts contain abundant acidophilic cytoplasm formed in bone marrow and function in the absorption and removal of osseous tissue. |
| Howship's lacunae | absorption lacunae. tiny cup shaped depressions on the resorbing front of any hard tissue, the result of resorptive activity by osteoclasts. |
| developmental or primary cuticle | finallym after the ameloblasts have completed their contributions to the mineralization phase, they secrete an organic cuticle on the surface of the enamel. |
| cementoblasts | large cuboidal cell lying on the surface of the bonde that is active in cementum formation. |
| cementocyte | a cell found in the lacunae of cellular cementum. numerous cytoplasmic processes extend from its free surface. |
| acellular cementum | that part of the cementum covering one third to one half of the root of a tooth adjacent to the cementoenamel junction. it consists of collagenous fibers and ground substance. |
| cellular cementum | that part of the cementum covering the apical one half to two thirds of the root of a tooth. this cementum is most abundant on the root tip. |
| intermediate cementum | a deposition by the epithelial oot sheath cells on the root surface fromed during root formation. may be termed enameloid. |
| accessory root canals | secondary canal extending from the pulp to the surface of the root, usuall found near apices of the root. |
| crypt | pitlike depressions or tubular recesses on a free surface. |
| pre-eruptive phase | developmental stage preparatory to eruption of teeth and characterized by monements of the growing teeth within the alveolar process. |
| prefunctional phase | phase of eruption that starts with the initiation of root formation and ends when the teeth reach occlusal contact. |
| functional phase | phase in which teeth reach incisal or occlusal contact and then undergo functional eruptive movements, which include compensation fro jaw growth and occlusal wear of the enamel. |
| movement | occurs incisally of occlusally through the bony crypt of the jaws to reach the oral mucosa. is the result of a need for space in which the enlarging roots can form. |
| clinical crown | that portion of the crown exposed and visible in the oral cavity. |
| anatomical crown | that portion of the tooth covered by enamel |
| fundic bone | bone enclosing the apex of the tooth root. |
| mesial drift | general movement of a tooth or teeth anteriorly toward the midline of the jaw. |
| ankylosis | abnormal stiffening and immobility of a joint due to fusion of the bones. |
| Predeciduous | the epithelial structures in the mouth of the infant before the eruption of the primary teeth. |
| deciduous teeth | are the first set of teeth in the growth development of humans |
| enamel rods | of the structural units of enamel, extending from the dentinoenamel junction to the surface of the tooth and normally having a translucent crystalline appearance. |
| enamel crystals | hydroxyapatite crystals found in enamel rods. they are formed during tooth mineralization. |
| organic matrix | formative portion of a tooth or bone as opposed to mineralized hydroxyapatite. |
| amelogens | protein found in newly deposeted enamel matrix. amelogenins are lost during maturation of ename. |
| enamelins | a major protein of immature enamel |
| lamellae | thin leaf or plate, as of bone. Thin sheets of organic material in enamel that extend from the surface to the dentinoenamel junction. |
| tufts | narrow, ribbon like structures whose constricted inner end arises at or near right angles to the dentinoenamel junction and extends a third of the way into the thickness of the enamel. tufts consis of hypocalcified spaces filled with organic substances. |
| spindles | the termination of dentinal tubules in inner enamel. |
| lines of Ritzius' | lines reflecting successive incremental deposition of mineralized enamel. |
| Hunter-Schreger bands | alternating dard and light bands in enamel that result from avsorption and reflection of light caused by defferences in orientation of adjacent groups of enamel rods originating at the dentinoenamel junction and extending toward the outer enamel surface. |
| gnarled enamel | the enamel located at the tips os the cusps, in which the rods or groups of rods are twisted, bent, and intertwined. it is seen ultrastructurally. |
| perikymata | wavelike trasverse grooves and ridges believed to be manifestations of the striae of retzius on the surface of the enamel. they appear transverse to the long axis of the crown. |
| neonatal line | accentuated incremental or gesitation line seen in bone, dentin, and enamel, probably caused by changes occuring at or near birth.. |
| Tome's Process | specialized apical zone of the ameloblasts. Tomes' process is conical and interdigitates with the forming enamel rods. |
| Terminal bar apparatus | localized condensations sytoplasmic substance associated with the cell membrane of the apical area of the functional ameloblast |
| dentinogenesis | the process of dentin formation in the development of teeth. |
| mantle dentin | the initially deposeted portions of the dentin formed immediately adjacent to the enamel |
| circumpulpal dentin | inner portion of the dentin located near the pulp organ of the tooth |
| reparative dentin | deposited after trauma to the tooth by the original odontoblasts. a defensive reaction whereby hard tissue formation walls off the pulp from the site or injury |
| incremental lines | an evident line produced through a rhythmic, recurrent deposition of successive layers upon present layers |
| globular dentin | areas of defective growth with interglobular spaces tha underlie the enamel and surface of the root |
| dead tracts | empty tubules resulting from loss of the odontoblastic processes |
| sclerotic dentin | dentin in which the tubules are occluded with mineral. occurs mostly in elderly people especially in the roots of the teeth. |
| Tome's granular layer | the layer of dentin is found only in the tooth root. it is adjacent to the peripheral zone of hyalinized root dentin as a thin, hypomineralized layer. |
| Gap junction | specialized communicating junction between cells with pores permeable to ions and small molecules |
| tight junction | allow electrical stimuli to pass from one cell to another |
| desmosomes | cell junction. it consists of a dense plate near the cell surface that relates to a similar structure on an adjacent cell, between which are thin layers of extracellular material. |
| type I collagen | bone, dentin, and cementum are what type of collagen |
| type II collagen | articular cartilage and hyaline cartialge |
| type III collagen | pulp porper and peridontal ligaments |
| hemidesmosome | half a desmosome that forms a site of attachment between epithelial cells and the basal lamina or between epithelial cells and the tooths surface. |
Created by:
renlynnb
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