Anatomy Ii Week 6: Odontogenesis

Front 1

When does tooth development begin? end?

1st thing formed?

Back 1

-5th week
-25yrs (roots of 3rd molars)

-dental lamina

Front 2

Embryonic origin:
enamel
dentin
pulp

Back 2

-ectoderm
-neural crest mesenchyme
- " "

Front 3

What tooth tissues(/structures) are mainly of neural crest-derived mesenchymal origin? (5)

Back 3

-dentin
-pulp
-cementum
-periodontal lig
-alveolar bone proper (dental follicle)

Front 4

List the 6 stages of tooth devpt

Back 4

-bud (initiation)
-cap (proliferation)
-bell
-crown
-root
-eruption

Front 5

Bud stage (4)

Back 5

-1st stage
-early 6th week
-ectoderm invaginates into mesenchyme
-progresses bilaterally from midlines

Front 6

Cap stage (3)

Back 6

-2nd stage
-histodifferentiation begins
-enamel organ, dental papilla, and dental follicle appear

Front 7

Layers of enamel organ (3)

Back 7

-inner enamel epithelia
-outer enamel epithelia
-stellate reticulum

Front 8

bell stage (4)

Back 8

-3rd stage
-histodifferentiation ends
-stratum intermedium is added to enamel organ
-morphodifferentiation occurs

Front 9

Crown stage (2)

Back 9

-4th stage
-enamel and dentin matrices laid down

Front 10

root stage (2)

Back 10

-5th stage
-begins after crown is complete

Front 11

Eruption (2)

Back 11

-6th stage
-movement of tooth into functional position

Front 12

devpt of each tooth is characterized by a series of _________________ interactions, which lead to (3)

Back 12

-epithelial-mesenchymal

-initiation of toothbud
-proliferation and morphodifferentiation
-cytodifferentiation

Front 13

Jaw mesenchyme induces

Back 13

-formation of dental lamina (initiation)

Front 14

dental lamina signals the __________ to become __________

Back 14

-jaw mesenchyme
-dental mesenchyme

Front 15

dental mesenchyme signals cells of the dental lamina to _____, differentiate into ______, and begin to form ________

Back 15

-invaginate (bud stage)
-enamel organ (cap stage)
-the shape of the crown (bell stage)

Front 16

enamel knot

Back 16

-signaling center
-determins cusp shape and location
-important during bell stage?

Front 17

cells of dental papilla signal cells of _______________ to become

Back 17

-inner enamel epithelium
-preameloblasts (late bell stage)

Front 18

preameloblasts induce formation of ________, which differentiate and begin to secrete _______

Back 18

-odontoblasts
-dentin matrix

Front 19

What happens with the mineralization of the first layer of dentin?

Back 19

-ameloblast differentiation is complete
-enamel matrix is formed

Front 20

molecular mech of tooth devpt

Back 20

-unknown
-appears that ECM components (fibronectin, laminin 5, tenascin) and diffusable growth factors (FGF, etc), and homeotic gene products (Msx1, etc) are involved

Front 21

tooth determination

Back 21

-unknown
-perhaps overlapping functional domains of "pattern formation" genes (Msx, etc) define the dental morphogenic fields

Front 22

cytodifferentiation

Back 22

-results in functionally specific cell types

Front 23

what differs in the devpt stages of each teeth

Back 23

-nothing except timing (which is based on position)

Front 24

primary epithelial band

Back 24

-presumptive dental epithelium
-formed by proliferation of ectoderm

Front 25

What is the inducing relationship of oral ectoderm and presumptive dental mesenchyme

Back 25

-oral ectoderm induces formation of presumptive dental mesenchyme
AND
-dental mesenchyme induces oral ectoderm to form dental lamina

Front 26

primary epithelial band becomes

Back 26

-dental lamina
-vestibular lamina

Front 27

vestibular lamina:
was
becomes

Back 27

-formed by primary epithelial band
-will degenerate and form vestibule

Front 28

dental lamina --> teeth

Back 28

-downgrowth in 10 specific sites result in teeth (bud stage)

Front 29

toothbuds:
which are the 1st to appear
all deciduous have begun forming
permanent
permanent molars

Back 29

-mand incisors
-8th week
-20th week, 10th month after birth
-20th week prenatal, 5th year postnatal

Front 30

what establishes tooth form and bilateral symmetry

Back 30

-originally dental epithelium
-after formation of enamel organ and dental papilla, then mesenchyme takes over

Front 31

histodifferentiation

Back 31

-transforming epithelial cells into morphologically and functionally distinct components

Front 32

morphodifferentiation

Back 32

-individual tooth buds attain recognizable shapes (incisor vs molar)

Front 33

what does the inner dental epithelium differentiate into (2)

Back 33

-stratum intermedium (outer layer)
-preameloblasts (columnar cells, inner layer)

Front 34

how do the inner dental epithelium cells change when they become preameloblasts?

Back 34

-cell appears to elongate
-nucleus, RER, Golgi, etc, move away from basal surface of cell
-:.secretory end of cell sits next to basement membrane

Front 35

when do true ameloblasts differentiate and what do they begin to synthesize

Back 35

-with the initial formation of dentin matrix
-enamel matrix (appositional or crown stage)

Front 36

How do messages pass btw epith and mesenchyme?

Back 36

-unknown. 3 hypotheses:
-paracrine stim by a hormone-like messenger
-cell-to-cell contact (minor role)
-specialized components in ECM btw epith and mesenchyme (eg. BM)