General Connective Tissue Lec 3-4

Question 1

What are the functions of Elastic fiber.

Answer 1

Permit tissues to be:

Stretch or distended and then returned to their original shape or form

Question 2

How do elastic fibers look when stained with H&E (Hematoxylin&Eosin)

Answer 2

Elastic fibers stain acidophilic in a shade of pink…very similar to collagen. Once in is used to highlight the elastic fibers.

In specially stained tissue spreads and sections, elastic fibers often look like dark brown or black “rubber bands” that have stretched then recoiled.

Question 3

How are Elastic fibers formed.

Answer 3

FIBRILLIN MICROFIBRILS deposited 1st

ELASTIN is then deposited on scaffold 2nd

Question 4

What is the FUNCTION of collagen?

Answer 4

It provides TENSILE STRENGTH to tissues (Resists shearing & tearing forces, stretching)

FLEXIBLE but NOT ELASTIC

Question 5

What are the different types of FIBRILLAR Collage?

Answer 5

FIBRILLAR I, II, III

Question 6

What number is SHEET-FORMING Collagen?

Answer 6

Sheet-forming IV

Question 7

What is the assembly of a Fiber bundle? From small to big

Answer 7

1. TROPOCOLLAGEN-molecule(mature collagen molecule)
   2 FIBRIL-orderly alignment of TROPOCOLLAGEN molecules
2. FIBER- Bundles of fibrils
3. FIBER BUNDLES- bundles of fibers

Question 8

Where does the formation of Fibrillar collagen occur?

Answer 8

It occurs outside the cell (extrecellular)

Question 9

Do all FIBRILLAR COLLAGENS mature to the FIBRIL STAGE and go on to form fibers and/or fiber bundles?

Answer 9

NO

Question 10

What is the Periodicity of Collagen fibrils?

Answer 10

68nm periodicity

Question 11

What does it mean by PERIODICITY OF COLLAGEN FIBRILS?

Answer 11

Precise, repetitive pattern of light and dark bands.

Staggered assembly of TROPOCOLLAGEN molecules INTO FIBRILS (overlap & hole zone)

Question 12

Organization (TEM, Transmission Electron )

How can you identify a COLLAGEN FIBER under TEM?

Answer 12

By their PERIODICITY in longitudinal sections

Question 13

What type of collagen is the most abundant? (I,II,III,IV)

Answer 13

Type I Collagen, 90% of collagen in body.

Question 14

Where can you find Type I Collagen?

Answer 14

Sclera of eye (white part)
Dentin (teeth)
Organ Capsules
Scar tissue

Question 15

What is ECM, What is it composed off?

Answer 15

Extrecellular Matrix, composed of Blood Vessels, Fiber and Ground substance

Question 16

What is a Type 1 Collegen defect Clinical Correlation?

Answer 16

OSTEOGENESIS IMPERFECTA…..it is MULTIPLE AND REPEATED FRACTURES WITH MINOR TRAUMA….
a.k.a “Brittle-bone” disease

Question 17

Where is Type II collagen?

Answer 17

Cartilage and vitreous(Glassy, looks like glass)body of the eye

Question 18

What is the function is Type II Collagen?

Answer 18

Resistance to pressure (restrains peptidoglycan aggregate)

Question 19

What does Type II Collagen form?

Answer 19

Forms fibrils & slender fibers

Question 20

Does Type II collagen bundle?

Answer 20

NOPE

Question 21

What is a Type II Collagen Clinical Correlation?

Answer 21

ACHONDROPLASIA, growth plates do not form properly.

Question 22

What type of cartilage are the Epiphyseal (growth) plates composed of?

Answer 22

Composed of HYALINE CARTILAGE which is composed of TYPE II collagen

Question 23

T/F: Type I, II, III Collagen are under the FIBRILLAR Collagen category.

Answer 23

TRUE, (there are two categories of collagen…FIBRILLAR (I, II, III) and SHEET FORMING (IV))

Question 24

What’s Type III Collagen?

Answer 24

Fibrillar collagen that remains as fibrils, RETICULAR FIBERS (heavy glycosylated Type III collagen fibrils)

Question 25

What staining is better for Reticular fibers in order for them to be seen under LM?

Answer 25

SILVER STAINING, Characteristically stained black by Silver (argyrophilic)….H & E staining: seldom visible

Question 26

Can Reticular fibers be stained with PAS? Why?

Answer 26

YESS! Because they are GLYCOSYLATED!

Question 27

Do Type I, II, III Collagen have periodicity?

Answer 27

Yes they do

Question 28

What is a Type III Collagen Clinical correlation?

Answer 28

Ehlers-Danlos Syndrome, Hyperextensible skin, easy bruising. Early morbidity & mortality due to rupture of blood vessels and internal organs

Question 29

Where is Type III Collagen located?

Answer 29

In the dermis of the skin
Provides support for tissues that make up many internal organs
Supports blood vessels

Question 30

What is a type of Sheet-forming collagen?

Answer 30

Type IV collagen

Question 31

Does Type IV collagen have form fibrils?

Answer 31

Type IV collagen does NOT form fibrils. There is NO PERIODICITY so nooooo

Question 32

Where is Sheet-forming collagen Type IV located?

Answer 32

Located in Basal lamina (epithelium), external lamina (muscle and nerve)

Question 33

What is the function of Type IV collagen?

Answer 33

Support of epithelial cells, part of filtration barriers

Question 34

What is Ground substance? Is it amorphous?

Answer 34

Clear, viscous substance with high water content. When it’s processed you Ground substance is lost, so you can’t see it on a slide, it looks empty…Amorphous means: without a clearly defined shape or form…so YES Ground substance IS amorphous.

Question 35

Where is ECM located?

Answer 35

Occupies the space between the cells & fibers

Question 36

What 3 different types of molecules are present in the Ground substance?

Answer 36

1. Glycosaminoglycans
2. Proteoglycans & proteoglycans aggregates
3. (Multi) adhesive glycoproteins

Question 37

What charge do GAGs and proteoglycans have?

Answer 37

HIGHLY NEGATIVELY charged, HIGHLY SULFATED!!!

Question 38

What kind of dyes do GAGs, Proteoglycans and Proteoglycan Aggregates tend to stain with?

Answer 38

Tend to stain with BASIC DYES

Question 39

What are Multiadhesive Glycoproteins?

Answer 39

They are a Ground substance molecule

Question 40

What is the purpose of the Multiadhesive Glycoproteins?

Answer 40

They stabilize the ECM by binding cells to components of the ECM.