QUIZ 2 Tooth Development Flashcards
1
Q
what are two examples of patterning defects of human dentition?
A
tooth agenesis (absence of teeth) and cleidocranial dysplasia (development of 3rd layer of teeth)
2
Q
what is the paradigm for organogenesis? (tooth morphogenesis)
A
- positional information - where they need to be
- shape determination
- size variance
- cell proliferation and migration
- terminal differentiation
- specialized matrix foramtion
- programmed cell death
3
Q
all organs develop from ___ and ___ layers
A
epithelium and mesenchymal
4
Q
what guides organogenesis?
A
epithelial-mesenchymal interactions
5
Q
cell communication is mediated by ___
A
signaling molecules
6
Q
growth factors turn on transcription factors, which control which 3 things in development?
A
proliferation, differentiation, and apoptosis
7
Q
what is the difference between autocrine and intracrine signaling?
A
- autocrine signaling involves the cell releasing a factor that has an affect on itself
- intracrine involves the cell producing a factor that affects itself, but never actually leaves the cell first
8
Q
___ interactions are critical in development
A
cell-cell
9
Q
___ interactions dictate morphogenesis and differentiation
A
cell-matrix
10
Q
what does the cranial neural crest give rise to?
A
- ganglia and nerves
- adrenal medulla
- ectomesenchyme of bones and teeth
- dentin
- bone
- cementum
- periodontal ligament
11
Q
what is developed by 37 days in utero?
A
- stomatodeum or primitive mouth
- covered by primitive epithelium
- embryonic connective tissue also referred to as ectomesenchyme
12
Q
describe the dental lamina
A
- becomes the future tooth bud
- outer primary epithelial band
- ectomesenchyme below (cells are more loosely packed)
- meckel’s cartilage within ectomesenchyme
13
Q
cell proliferation at the dental lamina causes ___
A
thickening
14
Q
label this photo
A
15
Q
what are the six stages of crown development?
A
- initiation - induction
- bud stage - proliferation
- cap stage - proliferation, differentiation, morphogenesis
- bell stage - proliferation, differentiation, morphogenesis
- apposition stage - induction and proliferation
- maturation stage - maturation
16
Q
what are the structures formed in the initiation stage?
A
lamina and bud
17
Q
what are the structures formed in the morphogenesis stage?
A
cap and early bell
18
Q
what is the structure formed in the cell terminal differentiation stage?
A
late bell
19
Q
what structures are formed in the matrix synthesis stage?
A
dentin, enamel, and cementum/bone
20
Q
what stage of development is the tooth type (incisor, premolar, molar, etc.) determined?
A
morphogenesis stage (cap, early bell)
21
Q
proliferation of epithelium produces buds at how many locations along each dental lamina?
A
10
22
Q
each bud is the precursor of the ___ for each deciduous tooth
A
enamel organ
23
Q
at the bud stage, ___ acts along with ___, ___, and ___ to stimulate the mesenchyme to express transcription factors ___, ___, ___, and the ECM molecules ___ and ___, and more ___
A
- at the bud stage, BMP-4 acts along with Fgf-8, Lef-1, and shh to stimulate the mesenchyme to express transcription factors, Msx-1, Msx-2, early growth response-1 (Egr-1), and the ECM molecules syndecan and tenascin and more BMP-4.
24
Q
what is induction?
A
the process where one tissue changes the development of surrounding tissues
25
what does Lef-1 do in the initiation stage of tooth development?
stimulates the pre-dental ectoderm to produce Fgf-8
26
what does Fgf-8 do in the initiation stage of tooth development?
induces the underlying mesenchyme to express Pax-9 and Msx-1 beneath the thickened dental lamina
27
what do BMP-2 and BMP-4 do?
inhibit Fgf-8
28
label this photo
what stage of tooth development is depicted?
early cap stage
a condensation of the ectomesenchyme associated with the epithelial cap is identified easily
29
label this photo
what stage of tooth development is depicted?
cap stage
the epithelial enamel organ sits over a mass of ectomesenchymal cells, the dental papilla that extends around the rim of the enamel organ to form the dental follicle
30
in the cap stage, unequal proliferation of ___ cause a cap to form
bud cells
31
in the cap stage, ___ cells condense around the developing cap; these will become the ___ and \_\_\_
* ectomesenchymal
* dental papilla and dental sac
32
what makes up the tooth germ?
enamel organ + dental papilla + dental sac
33
in the cap stage, what forms on the lingual side of the dental lamina?
successional dental lamina
34
in the cap stage, ___ will give rise to the enamel organs of the permanent replacements for the ten deciduous teeth
successional dental lamina
35
label this picture
36
label this picture
what stage of tooth development is depicted?
advanced cap stage
37
what structure dictates how many cusps will form in a tooth?
the enamel knot
38
label this photo
what stage of tooth development is depicted?
early bell stage
the enamel organ seems to be divided by the enamel cord
39
which stage of crown development is described as the continued differentiation of the enamel organ that produces four distinct layers with different functions?
bell stage
40
in the bell stage, continued differentiation of enamel organ produces which four distinct layers?
* outer enamel epithelium
* stellate reticulum
* stratum intermedium
* inner enamel epithelium
41
the cervical loop, present at the ___ stage, is the junction of which two layers?
* bell stage
* outer enamel epithelium and inner enamel epithelium
42
in the bell stage, dental papilla cells continue to proliferate into which two types of cells?
outer dental papilla cells and inner dental papilla cells
43
in the bell stage, proliferating dental cells will eventually develop into what at a later stage?
periodontal tissues
44
what is the function of the outer enamel epithelium?
protective barrier for enamel organ
45
what is the function of the stellate reticulum?
supports enamel production
46
what is the function of the stratum intermedium?
supports enamel mineralization - alkaline phosphatase
47
what is the function of the inner enamel epithelium?
differentiate into ameloblasts - enamel forming cells
48
describe the apposition stage of crown development
* organic matrix of enamel and dentin are laid down followed by initial calcification
* series of reciprocol inductions occur between enamel organ and dental papilla outer cells
49
in the apposition stage, reciprocol induction occurs in which order?
* IEE cells differentiate into preameloblasts - cells become polarized
* preameloblasts induce outer DP cells to differentiate into preodontoblasts which continue differentiating into odontoblasts
50
label this picture
the epithelial-mesenchymal interface
51
label this picture
the epithelial-mesenchymal interface
52
label this picture
epithelial-mesenchymal interface
53
label this picture
epithelial-mesenchymal interface
54
label this picture
55
what are the 7 stages of the ameloblast life cycle?
* inner enamel epithelial cell
* preameloblast
* initial secretory ameloblast
* secretory ameloblast
* smooth-ended maturation ameloblast
* ruffled-ended maturation ameloblast
* protective ameloblast
56
describe apposition and maturation patterns in crown development
apposition and maturation of dentin and enamel occur in increments from the cusp or incisal tip in a cervical direction
57
what is formed in the maturation stage?
dentin
58
\_\_\_ is mineralized as it is deposited
dentin
59
initial mineralization of dentin in the maturation stage is in the form of globules, producing \_\_\_
globular dentin
globules fuse together as mineralization proceeds
60
the initial layer of dentin next to the DEJ is called \_\_\_
mantle dentin
61
what is mantle dentin?
* collagen fibers perpendicular to the DEJ
* higher mineral contect
62
the intial layer of dentin next to the DEJ is called mantle dentin. the remaining dentain around the pulp is called \_\_\_
circumpulpal dentin
63
describe circumpulpal dentin
* collagen fibers parallel to DEJ
* lower mineral content
64
label this picture
65
describe dentin root development
* REE grows in an apical direction at the cervical loop
* becomes hertwig's epithelial root sheath (HERS)
* HERS induces DP outer cells to become odontoblasts
* root odontoblasts secrete predentin which is soon mineralized
* HERS then detaches from root dentin and disintegrates - some remnants persist as epithelial rests of malassez
* roots are not complete until after the tooth has erupted and is in function
66
label this picture
67
describe cementum root development
* dental sac cells migrate in and contact new root dentin surface
* induction of dental sac cells to differentiate into cementoblasts
* cementoblasts secrete organic matrix (cementoid) on new dentin surface
* cementoid mineralizes into cementum
* in the apical 1/2 to 2/3 of the root, cementoblasts become entrapped in lacunae as cementocytes
68
in multiroot development, ___ splits into two or three sheaths
HERS
69
describe the development of the periodontal ligament
* dental sac ectomesenchyme cells differentiate into fibroblasts
* fibroblasts secrete collagen fibers
* collagen fibers become anchored in cementum as it is deposited by cementoblasts
70
describe development of alveolar bone
* dental sac ectomesenchyme cells differentiate into osteoprogenitor cells then osteoblasts and lay down alveolar bone
* developing collagen fibers of the PDL become anchored in alveolar bone
