Development Of Enamel, Dentin, Cementum 1/18,25,27

Front 1

Differentiation of Odontogenic cells and tissues.

What's the cervical loop?

Back 1

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).

Front 2

Components of basal lamina

Back 2

. 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)

Front 3

Describe condensation of odontoblasts

Back 3

occurs in short period of time and space. Quickly differentiate into functioning odontoblasts. Ameloblasts will cover whatever the odontoblasts create.

Front 4

What are matrix vesciles? what do they contribute to?

Back 4

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.

Front 5

What occurs after mantle dentin formation?

Back 5

removal of basal lamina

Front 6

name the layers created through dentinogenesis.. what's seperates the odontoblast in the dentin from the enamel in the ameloblast

Back 6

DEJ. ameloblasts takes tomes process w/ them but odontoblasts leave the cytoplasmic processes behind

Front 7

4 stages of enamel organ

Back 7

presecretory, secretory, transitional, and maturation

Front 8

Describe Presecretory Stage

Back 8

ameloblasts differentiate, modify basement membrane. Induction – reciprocal signaling w/ mesenchyme. Remove basement membrane

Front 9

Describe the tomes process

Back 9

tip is responsible for rod/prism secretion. Those that are more proximal secrete the inter rod. inter rod secreted first.

Front 10

How many ameloblasts make 1 rod?

Back 10

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

Front 11

cadherin?

Back 11

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.

Front 12

catenin?

Back 12

catenins – necessary for cadhenin function( Beta or gamma); p-120 stabilized E cadherin to membrane; alpha- catenin connects B or gamma catenin to cytoskeleton.

Front 13

What's APC?

Back 13

APC – responsible for turnover for beta catenin.
- tumor suppressor protein, mutations result in polyps.
- abundantly expressed in ameloblasts
- regulates Beta catenin

Front 14

Amelogenins (AMEL)

Back 14

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

Front 15

Enamelins (ENAM), glycosylated

Back 15

disappear in maturation stage
AI autosomal chromosome 4q21

Front 16

Ameloblastins (AMBN)

Back 16

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

Front 17

Tuftelin

Back 17

In early secretory stage ameloblasts
Not isolated from matrix – not secreted

Front 18

Enamelysin (MMP20) metaloprotease

Back 18

Cleaves amelogenin
Localizes mostly to secretory stage
Enamelysin Knockout mice
altered rod pattern
Hypoplastic enamel, malformed maturation stage,

Front 19

Kallikrein-4 (KLK-4) serine protease Formerly EMSP-1

Back 19

Cleaves amelogenin in vitro
Localizes to the maturation stage

Front 20

Name the enamel matrix functions

Back 20

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

Front 21

What happens during the transitional stage?

Back 21

1. Ameloblasts become shorter and change function
2. Other cells of the enamel organ differentiate into papillary cells
3. anastomosing fenestrated capillary network

Front 22

What happens during Maturation Stage?

Back 22

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.

Front 23

What are SIBLINGs?

Name some examples!

Back 23

small integrin binding liagand, N linked glycoproteins.

Bone sialoprotein (BSP)
osteopontin-OPN (very little dentin)
Dentin matrix protein (DMP1- phosphorylated, Ser, Asp

DSPP

Front 24

What is the common ancestor of glycoproteins?

Back 24

SPRC-like 1

Front 25

What are proteoglycans ? Name some examples?

Back 25

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