Histology And Embryology Part 2

Front 1

Each germ contains ___ chromosomes (haploid number) during the process of fertilization, the number of chromosomes is restored to ___ (diploid number)

Back 1

23, 46

Front 2

The developing organism goes through 3 series of mitotic divisions. What are they?

Back 2

morula

blastocele

blastocyst

Front 3

morula

Back 3

16-32 cells, appearance resembles that of a mulberry

Front 4

blastocele

Back 4

a central cavity with an embryonic pole

Front 5

blastocyst

Back 5

thin-walled hollow ball of cells that attaches to and embeds in the uterine wall; two distant layers become visible.

1. epiblast (ectoderm) layer

2. hypoblast (endoderm) layer

**these two layers constitute the embryonic disc, which will give rise to the future embryo

Front 6

What are the three distinct periods of human development?

Back 6

1. period of the ovum (first week)

2. embryonic period (second week to eighth week) most organs systems develop, most congenital malformations occur here!

3. fetal period (third month to ninth month)- growth of existing structures

Front 7

development of some facial and oral structures is dependent on a group of cells called?

Back 7

neural crest cells derived from the ECTODERM as the neural tube is forming; develop the facial skeleton, neck skeleton, connective tissue components, and tooth development

Front 8

Initiation of the development of the oral cavity occurs in which prenatal week? and its complete by which week?

Back 8

Third prenatal week (embryonic period) and is complete in the 12th week

Front 9

At the beginning of the ___ week, 5 facial swellings, called branchial arches, appear on the embryo

Back 9

4th week

Front 10

oral stomodeum (primitive oral cavity)

Back 10

Located between the first branchial arch and the frontal process (forebrain); first sign of facial development

Front 11

The maxilla and the mandible develop from which branchial arch?

Back 11

first branchial arch

Front 12

The second to fifth brachial arches are involved in the development of what?

Back 12

the neck

Front 13

On the lower aspect of the frontal process, nasal pits (nostrils) arise from what?

Back 13

nasal placodes- these separate the lower frontal process into medial nasal process and the lateral nasal process

Front 14

medial nasal process

Back 14

area between the nasal pits, gives rise to the:

1. center of the nose and nasal septum

2. globular process that develops into the philtrum and primary palate (premaxilla)- anterior portion of palate

Front 15

lateral nasal process

Back 15

area to the right and left of the nasal pits, forms the sides of the nose

Front 16

frontal process includes:

Back 16

median nasal process

lateral nasal process

globular process

Front 17

Branchial arch 1 includes:

Back 17

maxillary process

mandibular process

Front 18

cleft lip

Back 18

occurs more often on the LEFT side

more in MALES

at the end of the SECOND MONTH

Front 19

cleft palate

Back 19

occurs more often in FEMALES

at the end of the THIRD MONTH

Front 20

The tongue develops during which week in embryonic life?

Back 20

4th week

Front 21

How does the tongue develop?

Back 21

from several swellings arising on the internal aspect of the branchial arches 1 to 4; these swellings eventually marge and form the body and root of the tongue

Front 22

brachial arch 1-2 lateral swellings and one medial swelling merge to form the ___ of the tongue

Back 22

body

Front 23

brachial arches 2, 3, and part of 4 merge to form the ___ of the tongue

Back 23

base

Front 24

brachial arch 4 also forms what?

Back 24

the epiglottis

Front 25

where does the thyroid gland develop?

Back 25

from an invagination of ectoderm in the area of the foramen cecum of the tongue; it eventually migrates down to its position in the neck

Front 26

thyroid tissue that remains entrapped in the tissue of the tongue is a developmental abnormality known as?

Back 26

lingual thyroid nodule

Front 27

when does tooth development begin?

Back 27

in the 7th week of embryonic life with 20 primary teeth

Front 28

each tooth consists of four tissues, what are they?

Back 28

enamel- calcified

cementum-calcified

dentin- calcified

pulp- un-calcified

Front 29

All tissues of the tooth are specialized forms of connective tissue expect?

Back 29

enamel; its epithelium

Front 30

Each tooth is the product of two tissue that interact during tooth development that include what?

Back 30

1. mesenchyme (ectomesenchyme)- derived from neural crest cells

2. epithelium- oral epithelium derived from the ectoderm

Front 31

what are the two major events that take place during tooth development?

Back 31

1. morphodifferentiation- shaping of the tooth

2. cytodifferentiation- cells differentiating into specific tissue-forming cells

Front 32

what are the 4 different tissue-forming cells in tooth formation?

Back 32

1. ameloblasts- enamel-forming cells

2. cementoblasts- cementum-forming cells

3. odontoblasts- dentin-forming cells

4. fibroblast- pulp-forming cells (can also become chondroblast, collagenoblast, or osteoblast)

Front 33

what two tissue types are responsible for shaping the tooth in morphodifferentiation?

Back 33

oral epithelium and underlying ectomesenchyme

Front 34

T or F: both primary and permanent teeth go through the same stages of development

Back 34

true

Front 35

what are the 8 stages of MORPHODIFFERENTIATION?

Back 35

1. bud stage

2. cap stage

3. bell stage

4. dentinogenesis

5. ameogenesis

6. apposition stage

7. eruption stage

8. functional stage

Front 36

bud stage

Back 36

condensed areas of ectomesenchymal cells that are continuous with the oral epithelium; connection between the two is referred to as the dental lamina

Front 37

cap stage

Back 37

future shape of tooth becomes evident; cells specialize to form the enamel organ

Front 38

bell stage

Back 38

final stage of morphodifferentiation; in the latter part of this stage; cytodifferentiation begins in the enamel organ

Front 39

dentinogenesis

Back 39

origin or initial stages of dentin formation

Front 40

amelogenesis

Back 40

differentiated cells begin initial enamel formation

Front 41

apposition stage

Back 41

formation of dental tissue matrix; this matric will then undergo maturation or calcification

Front 42

eruption and root development

Back 42

eruption and root development

Front 43

functional stage

Back 43

tooth is fully erupted in the mouth

Front 44

T or F: both cytodifferentiation and morphodifferentiation overlap; both epithelial and mesenchymal components of the tooth germ become organized.

Back 44

true, true

Front 45

epithelial components become the enamel organ, which is organized into four distinct cell layers, what are they?

Back 45

1. outer enamel epithelium (OEE)

2. inner enamel epithelium (IEE)

3. stratum intermedium (STI)

4. stellate reticulum (STR)

Front 46

outer enamel epithelium (OEE)

Back 46

outlines the shape of the future developing enamel organ on the outer surface composed of small cuboidal cells, one cell layer thick

Front 47

inner enamel epithelium (IEE)

Back 47

innermost layer of the enamel organ on the concave side of the developing tooth germ; this will become the future enamel producing cells, the ameloblasts, composed of cuboidal-type cells, one cell layer thick

Front 48

stratum intermedium (STI)

Back 48

flat, supporting, squamous type cells, two or three layers thick, lying on top of the inner enamel epithelial cells

Front 49

stellate reticulum (STR)

Back 49

mechanically and nutritionally supporting cells that fill the bulk of the developing enamel organ; are star shaped with large amounts of intercellular space between them

Front 50

mesenchymal components become subdivided into what?

Back 50

dental sac- forms the PDL, produces cementum, and alveolar bone

dental papilla- differentiate into odontoblast

center of papilla (becomes pulp)

Front 51

tooth development depends on ___ interactions between the epithelial and mesenchymal components of the tooth germ

Back 51

4 interactions

Front 52

first interaction

Back 52

ectomesenchyme instructs the epithelium to grow down into the ectomesenchyme and shape the tooth

Front 53

second interaction

Back 53

signal given by cells of the inner enamel epithelium (preameloblasts) to the mesenchymal cells on the periphery of the dental papilla to differentiate into odontoblasts and begin the deposition of dentin

Front 54

third interaction

Back 54

as soon as the odonoblast begin to deposit dentin, preameloblasts become true secreting ameloblasts and begin the deposition of enamel

Front 55

fourth interaction

Back 55

occurs with the development of root dentin and cementum

Front 56

what cell type are enamel-forming and dentin-forming cells?

Back 56

polarized, tall, columnar, secreting cells

Front 57

the permanent tooth germ grows off the primary by an epithelial attachment similar to the dental lamina called?

Back 57

successional lamina; this applied to all permanent teeth expect the 1st, 2nd, and 3rd molars which grow off of the dental lamina

Front 58

each ameloblast has a secretory process called ___, these have a six-pyramidal shape and are responsible for prism-shaped microscopic patterns of enamel rods; unlike the odontoblastic processes, tome's processes are NOT left behind when embedded in calcified tissue

Back 58

Tome's process

Front 59

dento-gingival junction formation

Back 59

after the enamel formation is complete, remains of the enamel organ (OEE, IEE, STI, and STR) come together to form the reduced enamel epithelium

Front 60

reduced enamel epithelium

Back 60

plays an important role in the formation of the dento-gingival junction as the tooth emerges into the oral cavity

Front 61

T or F: formation of tooth dentin and cementum follows after the formation of the crown of the tooth is complete

Back 61

true

Front 62

hertwig's rooth sheath (HERs)

Back 62

formed by the joining of the outer enamel epithelium and the inner enamel epithelium; grows down and shapes the root, formation of root dentin, produces the cementum, PDL, and alveolar bone

Front 63

what are the three types of stratified squamous epithelium found in the oral cavity?

Back 63

1. orthokeratinized

2. nonkeratinized

3. parakeratinized

Front 64

orthokeratinized

Back 64

effective an as mechanical protector and barrier against fluids, least common, layers include:

1. basal

2. prickle

3. granular

4. keratinized

Front 65

nonkeratinized

Back 65

functions as a selective barrier; acts as a cushion and as protection against mechanical stress and wear, layers include:

1. basal

2. prickle

3. outer surface of nonkeratinized cells- not recognizable

Front 66

parakeratinized

Back 66

intermediate form of the epithelium located between the orthokeratinized and nonkeratinized oral mucosa, layers include:

1. basal

2. prickle

3. keratinized

Front 67

what is the turnover time for stratified squamous epithelium?

Back 67

5 to 16 days

Front 68

connective tissue, aka lamina propria, is subdivided into two layers which are?

Back 68

papillary layer- right under epithelial layer; tattoo die is injected into this portion of tissue

reticular layer- dense fibrous layer located under the papillary layer; wrinkles in the skin occur because of degradation of the reticular layer

Front 69

submucosa

Back 69

layer of loosely organized connective tissue, present only in areas that require a high degree of compressibility and flexibility (cheeks, soft palate), when present, its located between the lamina propria and areas of muscle tissue

Front 70

interface

Back 70

area of interdigitation between the oral epithelium and connective tissue

Front 71

epithelial extension into connective tissue are called?

Back 71

ridges or rete pegs

Front 72

connective tissue extensions into overlying epithelium are called?

Back 72

connective tissue papillae

Front 73

basement membrane

Back 73

located between oral epithelium and connective tissue; noncellular; 2 layers:

1. lamina luida

2. lamina densa

Front 74

inflammation causes a ___ in keratinization

Back 74

reduction

Front 75

friction, heat, and chronic irritation causes a ___ in keratinization

Back 75

increase

Front 76

what are the 3 classifications of oral mucosa?

Back 76

masticatory, lining, and specialized

Front 77

masticatory mucosa

Back 77

gingiva and hard palate (orthokeratinized epithelium covering)

Front 78

lining mucosa

Back 78

lips, cheeks, floor of mouth, ventral surface (under-side of tongue), soft palate, alveolar mucosa, (nonkeratinized epithelial covering)

Front 79

specialized mucosa

Back 79

found only on the top of tongue; covered with lingual papillae, most taste buds are found of the lingual papillae; isolated buds may be found on the soft palate and walls of the pharynx

Front 80

fungiform papillae

Back 80

located on the dorsal aspect of the tongue, mushroom shaped

Front 81

filiform papillae

Back 81

most abundant, found covering the entire top surface of the tongue, have no taste buds, elongated in cases of "hairy" tongue

Front 82

circumvallate papillae

Back 82

large, located in a V-shape groove at the base of tongue, encircled by a deep groove, mushroom shaped, taste buds located on their sides, small salivary glands (Ebner's glands) empty into surrounding grooves

Front 83

foliate papillae

Back 83

located along the sides of the tongue, near the base, taste buds may be located on only one of the sides

Front 84

what are the compositions of mature dentin?

Back 84

organic matter 18%

inorganic matter 70%

water 12%

Front 85

dentin begins to form in what stage?

Back 85

the late bell stage

Front 86

each cell process in mature calcified dentin is enclosed in a?

Back 86

dentinal tubule

Front 87

tubules follow a primary S-shaped curve pathway and ___ secondary S-shape curves along the length of the tubules

Back 87

secondary

Front 88

the first layer of dentin immediately adjacent to the DEJ is called ___ dentin

Back 88

mantle- has thicker and heavier Korff's fibers and is less calcified

Front 89

the remainder of the deposited dentin is called ___ dentin (around the pulp)

Back 89

circumpulpal- finer collagen fibers

Front 90

dentin the forms immediately around the odontoblastic process is called?

Back 90

peritubular dentin- is the first dentin to be decalcified by bacterial enzymes when exposed to caries

Front 91

intertubular dentin

Back 91

consists of large, coarse collagen fibers; less calcified

Front 92

primary dentin

Back 92

dentin deposited before completion of the apical foramen

Front 93

secondary dentin

Back 93

dentin formed after completion on the apical foramen; tends to be more calcified than primary dentin; forms at a slower rate

Front 94

reactive (reparative) dentin

Back 94

forms rapidly in localized areas where dental tubules have been exposed to external traumas such as caries, attrition, or bruxism, or thermal extremes

Front 95

sclerotic dentin

Back 95

forms when the dentinal fibers have been degenerated and the tubules becomes filled with calcium salts

Front 96

dead tracts

Back 96

dentinal tubules that remain unfilled after dentinal fiber degeneration

Front 97

interglobular dentin

Back 97

small areas of unmineralized dentin near the DEJ

Front 98

Tome's granular layer

Back 98

small unmineralized areas of dentin beneath the cementum (may play a role in root sensitivity)

Front 99

what are the cells of pulp tissue?

Back 99

fibroblast

histiocytes- found along blood vessels

lymphocytes

monocytes, PMNs, eosinophils, and plasma cells are found in diseased pulp

no fat cells are present

Front 100

what are the functions of the pulp?

Back 100

nutritive functions- rich blood supply

formative function- peripheral layer gives rise to odontoblasts

sensory function

protective function