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oral histology > OHIST_Tooth Development (prior to dentinogenesis) > Flashcards

OHIST_Tooth Development (prior to dentinogenesis) Flashcards

1
Q

when does the initiation of tooth development begin and what is the name of the thickened band where this will occur

A

36 days/ primary epithelial band

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2
Q

what are the 2 subdivisions of the primary epithelial band

A

dental lamina and vestibular lamina

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3
Q

dental lamina appears as a thickening of oral epithelium near the condensation of what type of tissue:

A

ectomesenchyme

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4
Q

what is the name of the lamina from which the permanent teeth will develop?

A

successional lamina

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5
Q

what week of gestation does the dental lamina begin to function and when does this functional state end?

A

6th week –> 15th years old

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6
Q

though tooth development is a continuous process - what are the 3 stages it can be divided into

A

1) bud
2) cap
3) bell

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7
Q

what is the general anatomy of a “bud stage”? what type of tissue cells are packed closely beneath and around the buds?

A

bud: rounded growth of epithelium / mesenchymal cells packed below & around.

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8
Q

bud stage: what shape cells are around the edges of the bud? in the center of the bud?

A

low columnar / polygonal

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9
Q

during cap: what type of cells aggregate to form the dental papilla?

A

ectomesenchymal cells (clustered “deep to” the enamel organ).

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10
Q

what will the dental papilla eventually form?

A

dentin and pulp

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11
Q

during which part of which stage does histodifferentiation begin?

A

end of cap stage

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12
Q

on a cellular level - what is happening in order for this ectomesenchyme to “condense” - i.e. how are they forming this glob and not pushing away from each other?

A

this ectomesenchymal condensation is caused by a lack of extracellular matrix secretion by the cells…. preventing separation

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13
Q

what is the name of the epithelial outgrowth that will eventually for the enamel

A

enamel organ

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14
Q

the peripheral cells adjacent to the inner dental epithelium will eventually enlarge and differentiate into what specific cell type

A

odontoblasts

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15
Q

there is also condensed ectomesenchymal tissue that surrounds the entire papilla and enamel organ… what is the name of this ad what 2 support structures will it eventually give rise to?

A

the dental SAC (dental follicle) / rise to periodontal ligament and cementum

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16
Q

what is the name given to the the extension of dental lamina that is connected to the enamel organ?

A

Lateral Lamina

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17
Q

when sectioning developing dental tissue, there is an artifact produced because the enamel organ is a sheet of proliferating cells and contains a concavity filled with ectomesenchyme - What is the name given to this space?

A

enamel niche

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18
Q

the inner and outer dental epithelium will eventually be organized into a curvy landmark called the:

A

cervical loop

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19
Q

what is the name of the densely packed clusters of nondividing epithelial cells projecting form the inner enamel epithelium into the dental papilla? they are visible during the cap stage of molars. what do scientists currently believe its role to be?

A

enamel knot / organizational center for cusp development

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20
Q

what is the term used to constitute the structure that encompasses the enamel organ, the dental papilla, and the dental follicle?

A

dental organ OR tooth germ

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21
Q

enamel knot precursor cells are first noted by expression of what gene? (letter/number)

A

p21

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22
Q

the enamel knot and enamel cord are temporary. they disappear before enamel formation starts. what is their function thought to be (besides the center for cusp development)

A

possibly a reservoir full of dividing cells for the growing enamel organ. (ODD statement in our notes - slide 17)

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23
Q

since histodifferentiation is said to begin in the end of the cap stage…. it also continues into the bell stage. during the bell stage another “fancy named” process begins. what is it?

A

morphodifferentiation

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24
Q

what 2 types of cells “define” themselves during histodifferentiation?

A

ameloblasts and odontoblasts

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25
Q

what assumes its final shape during morphodifferentiation

A

the crown of the tooth

26
Q

during the bell stage, the enamel organ is further divided into more layers - now 4 - what are they (from outer to inner)

A

1) outer dental epithelium
2) stellate reticulum
3) stratum intermedium
4) inner dental epithelium

27
Q

bell stage: the inner dental epithelium are short columnar cells that border the dental papilla. these cells will eventually become what specific type of “blast” cell

A

ameloblasts - they will form the enamel by differentiating into TALL columnar cells

28
Q

bell stage: These same inner dental epithelial cells influence the underlying mesenchymal cells in the dental papilla - causing these dental papilla cells to differentiate into what “blast” cells

A

odontoblasts

29
Q

bell stage: the outer dental epithelium is made up of what shape cells and what is their function?

A

cuboidal / they function to organize capillary network to bring nutrition to the ameloblasts. details: in preparation to form enamel, at end of bell stage, the ODE is laid in folds. the folds have dental sac mesenchyme that extends little papilla in between the folds. these papilla contain the capillaries that will support the metabolic activity of the avascular enamel

30
Q

stellate reticulum:

1) what do the look like /
2) what do they secrete /
3) what does this secretion cause /
4) what is their purpose
5) where is this cell layer located

A

1) star shaped with processes
2) secrete glycosaminoglycans
3) attract water, swell cells, which pushes them apart
4) cushion like to support and protect delicate enamel organ
5) btw outer and inner dental epith.

31
Q

stratum intermedium:

1) where is this cell layer located
2) what enzymatic activity is prominent in this layer
3) what important process is this enzyme needed for (i.e what process do they assist)

A

1) btw inner dental epith AND stellate reticulum (thin dark layer of cells)
2) alkaline phosphatase
3) AP is needed for calcification - it assists the ameloblasts of the inner dental epith to form enamel

32
Q

the basement membrane that separates the enamel organ and the dental papilla just prior to dentin formation is called the:

A

membrana preformativa - this will for the future DEJ - NOTE: Dr. Raj said this info was “just for boards”.

33
Q

the cervical loop is formed by the “joining/meeting” of what 2 layers of cells and it is critical for the formation of what tooth structure?

A

formed where the inner and outer dental epith. meet. critical for root formation.

34
Q

Bell stage: what is the term used to describe a pattern of enamel knot that extends btw the inner and outer dental epith.

A

enamel cord (dr raj does not know the significance of this yet) - slide 24

35
Q

bell stage: the dental lamina and the lateral lamina will disintegrate and separate away from the oral epithelium However, sometimes these epith cells will persist. What are they called (2 diff names)? Also, these can form cysts (eruption cysts). what are the 3 clinically significant things that these cysts can result in.

A

Epithelial pearls OR cell rests of Serre /

1) the cysts can prevent eruption
2) form odontomas (tumors)
3) form supernumery teeth

36
Q

crown pattern determination occurs during bell stage by folding of the inner dental epithelium. the Cessation of ___________ within this layer of epith is what determines the shape of the tooth

A

mitotic activity

37
Q

clustering of vessels in papilla coincide with the position of ________ formation

A

root

38
Q

nerve supply is first seen in the _______ ______ (2 words) during the ______ and _____ stages. however, after the start of _____, it is seen in the _______ _______

A

seen in the “dental follicle” / during “bud to cap” stage / after dentinogenesis / seen in dental papilla

39
Q

nerve fibers do not enter what part of the dental follicle

A

the enamel organ

40
Q

tumors of odontogenic epithelium arising from cell rests of enamel organ OR from the developing enamel organ are called what:

A

ameloblastomas - histologically resemble enamel organ BUT have loosely arranged stellate-reticulum-like-cells

41
Q

tumor of the jaw from odontogenic ectomesenchyme

A

odontogenic myxoma - histologically looks similar to mesenchymal portion of a developing tooth (like the dental papilla).

42
Q

where (relative to the deciduous tooth germ) do the permanent tooth germs develop.

A

lingual

43
Q

entire primary dentition initiated between ____ to ____ weeks of embryonic devel.

A

6 - 8

44
Q

successional permanent teeth initiated between ____ week in utero until the ____ month after birth

A

20th / 10th

45
Q

permanent molars (non succedaneous teeth - not replacing baby teeth) are initiated between ____ week in utero until _____ year of life

A

20th / 5th

46
Q

hard tissue formation starts at the late stages of the _______ stage

A

bell

47
Q

which is formed first - enamel or dentin

A

dentin

48
Q

regarding dentin & enamel —> which initiates the other to form.

A

dentin initiates the formation of enamel

49
Q

the deposition of dental hard tissues is termed:

A

apposition

50
Q

during cap/early bell…. when crown reaches final shape… all of the cells of the inner dental epith stop proliferating EXCEPT which ones

A

the cells at the cervical loop

51
Q

the first layer of dentin appears where and progresses in which direction

A

at the cusp tips / cervically

52
Q

after the first layer of dentin appears, the columnar cells of the inner DE elongated and what happens to the nucleus

A

the cells undergo “reverse polarization” and move to the end of the cell next to the stratum intermedium (ameloblasts) - slide 37

53
Q

the boundary btw the odontoblasts and the inner DE define what future anatomical landmark

A

DEJ

54
Q

the odontoblasts and ameloblasts “talk” to each other during their development - what is the term for this occurrence

A

reciprocal induction

55
Q

what are the 4 stages of apposition

A

1) elongation of inner DE
2) differentiation of odontoblasts from ameloblasts
3) formation of dentin
4) formation of enamel

56
Q

after the first layer of dentin (mantle dentin) is laid down, the inner DE cells differentiate into ameloblasts and secrete _____ ______. This secretion helps in the terminal differentiation of what specific cells?

A

enamel proteins / help in the terminal differentiation of odontoblasts.

57
Q

the presence of what type of fibers makes dentin have similarities to bone

A

type 1 collagen

58
Q

READ SLIDE 41 about apposition

A

apposition

59
Q

the differentiation of odontoblasts from ectomesenchymal cells is induced by the influence of what layer

A

the inner dental epithelium - experiments have shown that if there is no inner dental epith….. there is no dentin formed

60
Q

what layer of our teeth is the only layer that is PURELY ectodermal in origin? what layer is derived from ectomesenchyme?

A

enamel / dentin

61
Q

true or false: dentin is formed by _______ that differentiate from ____________ cells of the dental papilla with influence from the _______ _________ _______.

A

odontoblasts / ectomesenchymal / inner dental epithelium

oral histology (3 decks)

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