Histology and Embryology Flashcards

1
Q

Preimplantation Period

A

first week of conception

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2
Q

Embryonic Period

A

weeks 2 to 8

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3
Q

Fetal Period

A

weeks 9 to birth

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4
Q

Fertilization Stage

A

Preimplantation

formation of zygote

zygote receives 23 chromosomes from mom and 23 from dad

zygote undergoes mitosis and eventually becomes a blastocyst

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5
Q

Implantation

A

Preimplantation Period

by 7 days, the blastocyst will be endometrium

after one week, it will consist of a trophoblast layer (nutritive) and a embroblast layer (becomes embryo)

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6
Q

Bilaminar Disk

A

Embryonic Period

consists of a superior epiblast layer and an inferior hypoblast layer

disc is suspended between 2 spaces - the amniotic cavity and the yolk sac

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7
Q

Trilaminar Disk

A

Embryonic Period

Consists of Mesenchyme, Ectoderm, Mesoderm, Endoderm

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8
Q

Mesenchyme Layer

A

differentiates into different connective tissue

(odontoblasts, osteoblast, fibroblast ect)

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9
Q

Ectoderm

A

forms the epithelial enamel organ

(week 3 of embryonic period)

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10
Q

Mesoderm

A

forms during embryonic period

forms the dental papillae which differentiates into dental pulp and elaborates the dentin

called the dental sac

forms the cementum covering the root and periodontal membranes

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11
Q

Endoderm

A

forms during embryonic period

forms epithelial linings of the respiratory passages and digestive tract

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12
Q

Embryonic Folding

A

Last stage of Embryonic Period (end of week 9)

most organs and body systems are developed

most congenital malformation occurs in this stage

enlargement of embryo into a fetus

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13
Q

Period of Face Development

A

Weeks 3-12

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14
Q

First Brachial Arch

A

AKA Mandibular Arch

Divides into maxillary and mandibular processes

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15
Q

Mandibular Process

A

Lower parts of the face and lower lip

anterior ⅔’s of the tongue

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16
Q

What forms the posterior ⅓rd of the tongue and the hyoid bone?

A

Second and third brachial arches

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17
Q

Maxillary Process

A

Lateral palatine processes

upper parts of cheek

sides of upper lip (not philtrum)

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18
Q

Frontal Process

A

forhead and frontal bone

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19
Q

Median Nasal Process

A

Center and tip of nose

nasal septum

globular process (philtrum, premaxillary palate (anterior) )

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20
Q

Lateral Nasal Process

A

sides of nose

infraorbital area

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21
Q

Stomodeum

A

primitive mouth

lined by ectoderm, which will become oral epithelium

mesoderm differentiates into ectomesenchyme

Week 3

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22
Q

Period of Tongue Formation

A

Develops weeks 4 to 8

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23
Q

Filiform Papillae

A
  • *only papillae with no taste buds**
  • keratinized*

elongation known as hairy tongue

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24
Q

Fungiform Papillae

A

Few, large red bumps

contain taste buds

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25
Q

Foliate Papillae

A

folds of tissue at posterior, lateral boarder

contain taste buds

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26
Q

Circumvallate Papillae

A

8-12 in number

anterior to the sulcus terminalis

contains taste buds and glands of Von Ebner

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27
Q

Tongue Innervation

A

Hypoglossal: motor nerve

Trigeminal V3: sensory to anterior ⅔

Facial: taste to anterior ⅔ (via chorda tympani)

Glossopharyngeal: taste and sensory posterior ⅓

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28
Q

Extrinsic Muscles of the Tongue

A

hypoglossus ⇒ below

styloglossus ⇒ back

genioglossus ⇒ stick out tongue

palatoglossus ⇒ above tongue, prevents choking

29
Q

Period of Palatal Formation

A

Weeks 6 to 12

30
Q

Hard Palate Formation

A

Primary Palate (premaxilla) ⇒ anterior ⅓

Secondary Palate (formed from 2 palatal shelves) ⇒ posterior ⅔

NOTE: if 2 palatal shelves dont fuse, causes cleft palate

31
Q

Initiation Stage

(AKA Induction)

A

WEEKS 6-7

ectoderm gives rise to oral epithelium and dentinal lamina

Enamel is forming

32
Q

Bud Stage

(AKA Proliferation)

A

WEEK 8

dental lamina grows into mesenchymal (connective) tissue at 20 places to form primary teeth

enamel grows into dentin and pulp

33
Q

Cap Stage

A

WEEKS 9-10

  • enamel organ develops from dental lamina to produce enamel
  • Dental Papilla arises from specialized tissue to produce dentin and pulp
  • Dental Sac surrounds tooth and becomes PDL, alveolar bone, and cementum

PAC the SAC in CAP (PDL, alveolar bone, cementum from the dental sac)

34
Q

Bell Stage

A

WEEKS 11-12

Enamel Organ forms 4 layers

  • Outer Enamel Epithelium (forms hertwigs epithelial root sheath)
  • Stellate Reticulum
  • stratum intermedium
  • Inner Enamel Epithelium (becomes ameloblasts)

DEJ develops from basement membrane

  • odontoblasts formed
35
Q

Root Formation

A

occurs after the crown is complete and ends 1-4 years after eruption

36
Q

Apposition Stage

A

enamel, dentin, cementum are secreted in increments

Dentinogenesis: process of dentin matrix formation

Amelogenesis; process of enamel matrix formation

37
Q

Maturation Stage

A

dental tissues develop into their mature tissues and undergo calcification by deposition of hydroxyapatite crystals

38
Q

Hertwigs Epithelial Root Sheath

(HERS)

A

Develops from IEE and *OEE

dissolves after root formation

Has the potential to form cysts if remnants remain

39
Q

Cleft Palate

A

Failure of palatal shelves to fuse with each other

causes malpositioning of teeth and mouth breathing

weeks 8-12

obturator is used to correct and fuse palate

40
Q

Cleft Lip

A

Failure of fusion between maxillary process and median nasal process

weeks 4-7

usually unilateral

increases risk of oral infection, periodontal disease, caries, and malnutrition

41
Q

Enamel Composition and Origin

A

96% inorganic material

Ectoderm

42
Q

Lines of Retzius

A

dark incremental lines from mineralization on enamel

43
Q

Outer Enamel Organ

A

outlines the shape of enamel

44
Q

Inner Enamel Epithelium

A

*develops ameloblasts on concave side of enamel organ

45
Q

Stratum Intermedium

A

layer above IEE

46
Q

Enamel Spindles

A

ends of odontoblastic processes which cross the DEJ

47
Q

Hunter-Schreger Bands

A

light or dark bands of enamel perpendicular to DEJ

caused by curvature of enamel rods

48
Q

Perikymata

A

lines on enamel surface where lines of Retzius end

49
Q

Enamel Tufts

A

hypomineralization of enamel rods near DEJ

50
Q

Dentin Composition and Origin

A

70% inorganic material

Mesenchyme

51
Q

T/F Dentin Stays Vital Throughout the Life of a Tooth?

A

True

52
Q

Lines of Von Ebner

A

incremental dentinal lines of daily growth

53
Q

Tomes Granular Layer

A

outer portion of dentin beneath root cementum adjacent to DCJ

54
Q

Peritubular Dentin

A

dentin that formed immediately around odontoblastic process

more mineralized than other parts of dentin

55
Q

Intratubular Dentin

A

Less mineralized remaining dentin in between tubules

56
Q

Mantle Dentin

A

first layer of dentin next to the DEJ

57
Q

Circumpolar Dentin

A

layer of dentin around pulpal wall

58
Q

Production of Dentin

A

Produced by odontoblasts from dental papilla

59
Q

Primary Dentin

A

Deposited before completion of the root

60
Q

Secondary Dentin

A

Develops after tooth is in occlusion

Developed by odontoblasts in pulp

61
Q

Tertiary Dentin

A

formed in response to trauma

62
Q

Sclerotic Dentin

A

fully calcified dentin associated with chronic injury

63
Q

Cementum Formation

A

50% mineralized

produced by cementoblasts in PDL

64
Q

What nourishes cementum?

A

PDL

65
Q

Acellular vs Cellular Cementum

A

Acellular: found at CEJ (more coronal) THINNEST

Cellular: found at apex (more apical) THICKEST

66
Q

Where does is the root derived from?

A

cervical portion of enamel organ

IEE and OEE fuse together to elongate after crowns are formed

67
Q

T/F the root is fully formed when the crown erupts

A

False

68
Q

Importance of Pulp

A

vital, sensory, and responsive portion of the tooth

69
Q

What is Contained in Pulp?

A

blood vessles

nerve fibers

fibroblasts

odontoblasts

histocytes

pulp stones