Man-Kyo Chung, DMD, PhD
Assistant Professor
Department of Neural and Pain Sciences
University of Maryland Dental School
Proliferation (increase in number)
Migration (change in location)
Differentiation (specialization)
Ameloblasts forming enamel Odontoblasts forming dentin Cementoblasts forming cementum
epithelial cells
ectomesenchymal cells
Enamel
Dentin
Cementum
Pulp
zygote
(a cell from fertilization)
Mesoderm (connective tissues / heart, muscle, blood cells, bone, dermis etc)
Ectoderm (tissues covering outside the body /epidermis, hair , nails etc)
Endoderm (tissues lining inside the body / lung, stomach, intestine, liver etc)
<trilaminar germ disc>
Oral Histology and Embryology by Leslie
P. Gartner, 1988 bilaminar germ disc
<1 wk ~2 wks
~3 wks
3. connective tissues of head and neck (bone, cartilage, muscles, tooth etc)
epithelium
(Ectomesenchymal origin)
embryonic
connective tissue
ectodermal origin
ectoderm
neural tube
neural crest
1. brain (neuroectodermal origin)
2. sensory ganglia
6 weeks old embryo
Maxillary process
Mandibular process
Oral Histology and Embryology by
Leslie P. Gartner, 1988
auricle
eye
Coronal section
Oral epithelium of maxillary
and mandibular processes
tongue
nasal septum
1. Bud stage
2. Cap stage
3. Bell stage
4. Appositional stage (mineralization)
5. Root formation
6. Eruption
(bud-like outgrowth from dental lamina)
(further epithelial growth)
(histo- and morpho-differentiation)
(formation of enamel and dentin of crown)
(formation of dentin and cementum of root)
Oral Histology and Embryology by Leslie P. Gartner, 1988
* Initiation (band-like outgrouwth of oral epithelium)
Mx
Mn
dental lamina
Dental lamina
• At ~6 weeks of embryo
• outgrowth of epithelial band
from oral epithelium
• horse-shoe shape
• one dental lamina per arch
Mx
Mn
dental lamina
tooth bud
developing maxillalry bone
tongue
palate
http://www.iob.uio.no/studier/undervisning/histologi/index.php
• Tooth bud
- Localized outgrowth of epithelial cells
from dental lamina
- 10 tooth buds per lamina
developing mandibular bone
Mx
Mn
vestibular lamina
http://www.iob.uio.no/studier/undervisning/histologi/index.php
vestibule
ectomesenchymal cells
http://www.iob.uio.no/studier/undervisning/histologi/index.php
condensation of ectomesenchymal cells around tooth bud
http://www.iob.uio.no/studier/undervisning/histologi/index.php
1. Enamel organ (=dental organ) (proliferation of epithelial cells)
2. Dental papilla (condensation of ectomesenchymal cells)
3. Dental sac (=dental follicle) (capsule like condensation of ectomesenchymal cells)
1
2
3
http://www.iob.uio.no/studier/undervisning/histologi/index.php
1. Enamel organ
2. Dental papilla
3. Dental sac 1
2
3
enamel
dentin pulp
cementum periodontal ligament alveolar bone connective tissues of gingiva
http://www.iob.uio.no/studier/undervisning/histologi/index.php
1
2
3
http://www.iob.uio.no/studier/undervisning/histologi/index.php
Transformation of a cell mass into morphologically and functionally distinct components
Secreting proteoglycans (absorbing water increase extracellular space)
1) Outer enamel epithelium
2) Stellate reticulum
3) Inner enamel epithelium
desmosome
Flattened (squamous or cuboidal)
Star shaped
Elongated and polarized (columnar)
Enamel organ
2
1
3
1) Inner enamel ep
2) Outer enamel ep
3) Cervical loop
4) Stellate reticulum
5) Enamel knot
6) Enamel cord
7) Enamel navel
4
5
6
7
transient structure during cap stage
http://www.iob.uio.no/studier/undervisning/histologi/index.php
(inner+outer enamel ep.)
2
1
3
1) Inner enamel ep
2) Outer enamel ep
3) Cervical loop
4) Stellate reticulum
5) Enamel knot
6) Enamel cord
7) Enamel navel
4
5
6
7
transient structure during cap stage
root formation
generate enamel
location of cusp?
http://www.iob.uio.no/studier/undervisning/histologi/index.php
(protect inner enamel ep.)
Oral Histology and Embryology by Leslie P. Gartner, 1988
(tooth bud of
permanent tooth)
1. Tooth shape is identifiable.
2. Further differentiation of enamel organ
1) outer enamel ep.
2) inner enamel ep.
3) stellate reticulum
4) stratum intermedium
3
2
1 4
http://www.iob.uio.no/studier/undervisning/histologi/index.php
1. Tooth shape is identifiable.
2. Further differentiation of enamel organ
1) outer enamel ep.
2) inner enamel ep.
3) stellate reticulum
4) stratum intermedium
3
2
1 4
http://www.iob.uio.no/studier/undervisning/histologi/index.php
stratum intermedium
inner enamel ep
basement membrane
dental papilla
http://www.iob.uio.no/studier/undervisning/histologi/index.php
Oral Histology and Embryology by Leslie P. Gartner, 1988
Cusp
tip
root
differentiated
to ameloblast
without proliferation
Keep proliferating
and migrate
downward
older taller polarized
younger shorter unpolarized
http://www.iob.uio.no/studier/undervisning/histologi/index.php
1. oral ep.
2. outer enamel ep.
3. stellate reticulum
4. inner enamel ep.
5. dental papilla
6. cervical loop
3
2
1
5
4
6
blood
vessels
http://www.iob.uio.no/studier/undervisning/histologi/index.php
Stage of mineralization
oral epithelium
dental lamina
mesenchymal
cells bud
Cap
m
inera
liza
tion
bell
1
signal
proliferation
1
epithelium
mesenchyme
oral epithelium
dental lamina
inner enamel epithelium
preameloblast
mesenchymal
cells
preodontoblast
1
2
2
epithelium mesenchyme
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
10
11
12
13
a
b
c
d
e
f
g
h
i
a
b
c
d
e
f
g
h
i
j
k
l
m
Preameloblasts Preodontoblasts
bud
Cap
m
inera
liza
tion
bell
oral epithelium
dental lamina
inner enamel epithelium
preameloblast
ameloblast
mesenchymal
cells
preodontoblast
odontoblast
Predentin
enamel matrix
enamel
dentin
bud
Cap
m
inera
liza
tion
bell
1
2
3
odontoblasts preameloblasts
ameloblasts
Predentin (dentin matrix)
dentin enamel matrix
3
3
2
8
5
4
6 7
9
1 http://www.iob.uio.no/studier/undervisning/histologi/index.php
stratum intermedium
ameloblasts
enamel
dentin
predentin
odontoblasts
http://www.iob.uio.no/studier/undervisning/histologi/index.php