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25 Cards in this Set
- Front
- Back
Differentiation of Odontogenic cells and tissues.
What's the cervical loop? |
The cervical loop- cells are dividing. Mesenchymal cells aren’t doing much here. Basement membrane seperates endothelium from mesenchyme (between inner enamel epithelium and mesenchyme cells).
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Components of basal lamina
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. type IV collagen
b. anchoring fibers Type VII collagen- mesenchyme becomes attached here. c. laminin (LN) d. fibronectin (FN) e. Perlican f Integrin (intra-, trans-, and extracellular protein, has 2 subunits) |
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Describe condensation of odontoblasts
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occurs in short period of time and space. Quickly differentiate into functioning odontoblasts. Ameloblasts will cover whatever the odontoblasts create.
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What are matrix vesciles? what do they contribute to?
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Matrix vesicles- minerals first forms within membrane. Begin to fuse and eventually you get entire layer of mantle dentin. Meanwhile, odontoblasts continue to synthesize type 1 collagen.
7. Mantle dentin formation -- von Korff fibers – first dentin to be formed. Very thick and fat collagen fibers only found here. Mineralization through matrix vesicles. Only occurs here. |
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What occurs after mantle dentin formation?
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removal of basal lamina
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name the layers created through dentinogenesis.. what's seperates the odontoblast in the dentin from the enamel in the ameloblast
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DEJ. ameloblasts takes tomes process w/ them but odontoblasts leave the cytoplasmic processes behind
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4 stages of enamel organ
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presecretory, secretory, transitional, and maturation
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Describe Presecretory Stage
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ameloblasts differentiate, modify basement membrane. Induction – reciprocal signaling w/ mesenchyme. Remove basement membrane
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Describe the tomes process
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tip is responsible for rod/prism secretion. Those that are more proximal secrete the inter rod. inter rod secreted first.
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How many ameloblasts make 1 rod?
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old: 3 due to hexagonal key hole pattern.
new:1. The shampe of the TOme's process reflects the head and tail of the forming enamel rod |
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cadherin?
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cadherin – single pass transmembrane proteins; Ca dependent homophillic adhesion. Allows cells to stick to each other when they need to. Each cell type has different type of cadherin.
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catenin?
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catenins – necessary for cadhenin function( Beta or gamma); p-120 stabilized E cadherin to membrane; alpha- catenin connects B or gamma catenin to cytoskeleton.
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What's APC?
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APC – responsible for turnover for beta catenin.
- tumor suppressor protein, mutations result in polyps. - abundantly expressed in ameloblasts - regulates Beta catenin |
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Amelogenins (AMEL)
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90% of enamel matrix
rich in pro, hist, leu hydrophobic with one phosphorylation site enzymatic breakdown to 23kDa > 20kDa > TRAP (aa 1-45) alternate splicing - several mRNAs from 1 gene gene on X chromosome (Y 10% transcribed) sexual dimorphism in Hu many AI types associated with X-linked traits (AI also autosomal) 180 (murine) - 216 (bovine) amino acids: 9 exons: several isoforms LRAP = Exons 4, 5 and part of 6 missing due to alternative splicing Enzymatic cleavage, 28 kDa –25kDa-23kDa-20kDa- TRAP& peptides amelogenin knockout mice enamel is mineralized hypoplastic enamel, disorganized rod structure |
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Enamelins (ENAM), glycosylated
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disappear in maturation stage
AI autosomal chromosome 4q21 |
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Ameloblastins (AMBN)
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65kDa, glycosylated
5-10% of matrix Parent protein evenly distributed in enamel Quickly lysed to 30-20 kDa fractions found in prism sheath Disappear in maturation stage Ameloblastin KO mouse |
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Tuftelin
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In early secretory stage ameloblasts
Not isolated from matrix – not secreted |
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Enamelysin (MMP20) metaloprotease
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Cleaves amelogenin
Localizes mostly to secretory stage Enamelysin Knockout mice altered rod pattern Hypoplastic enamel, malformed maturation stage, |
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Kallikrein-4 (KLK-4) serine protease Formerly EMSP-1
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Cleaves amelogenin in vitro
Localizes to the maturation stage |
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Name the enamel matrix functions
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1. nucleate HAp crystlas
2). inhibit crystal growth in width and thickness 3) promote crystal growth longitudinally 4. glue crystal in place until they fuse |
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What happens during the transitional stage?
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1. Ameloblasts become shorter and change function
2. Other cells of the enamel organ differentiate into papillary cells 3. anastomosing fenestrated capillary network |
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What happens during Maturation Stage?
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ameloblasts resorb matrix proteins. Water is removed from matrix; matrix accumulates Ca and P.
1. Influx of Ca/P 2. ameloblasts modulations a Ruffle-ended b Smooth-ended 3. Cell junctions alternate apical to basal. |
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What are SIBLINGs?
Name some examples! |
small integrin binding liagand, N linked glycoproteins.
Bone sialoprotein (BSP) osteopontin-OPN (very little dentin) Dentin matrix protein (DMP1- phosphorylated, Ser, Asp DSPP |
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What is the common ancestor of glycoproteins?
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SPRC-like 1
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What are proteoglycans ? Name some examples?
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Protein core w/ GAGs.
Ex: Biglycan and Decorin - similar but usually in diff tissues -interact w/ TGFbeta, BMP4 Perlican in basement membrane syndecan - intra, trans, extracellular protein |