Connective Tissue

Question 1

Where is the origin of connective tissue cells

Answer 1

Mainly from undifferentiated mesenchymal cells

Haematopoietic stem cell line

Question 2

What are the constituents of connective tissue

Answer 2

Cellular component
- fibroblasts/cytes
- adipose tissue

Extracellular components
- visible fibres
- ground substance (hydrophilic jelly) - doesn’t stain with H&E appears white spaces

Question 3

What are the types of connective tissues

Answer 3

1. Fibrous (depending on collagen fibres within them)
   - Loose
   - Dense
2. Hard
   - Cartilage
   - Bone
3. Fatty
   - White (most prevalent of the fats)
   - Brown (role in thermogenesis)

Question 4

What is collagen

Answer 4

Secreted by fibroblasts as tropocollagen - triple helix of peptides

Fibres assembled extra-cellularly

Question 5

How many types of collagen are there

Answer 5

More than 20

Question 6

What is type 1 collagen prevalent in

Answer 6

Skin and bone

Question 7

What is type 2 collagen prevalent in

Answer 7

Cartilage

Question 8

What is type 3 (reticulin) collagen prevalent in

Answer 8

Liver, bone marrow, spleen

Question 9

What is type 4 collagen prevalent in

Answer 9

Basement membrane

Question 10

What is type 5 collagen prevalent in

Answer 10

Placenta

Question 11

What colour do collagen fibres stain with H&E

Answer 11

Extracellular - pink

Variable thickness and length - often run in bundles

Question 12

What is the significant difference between collagen fibres and muscle fibres

Answer 12

Muscle fibres are intracellular (nuclear lies within them)

Question 13

What does loose connective tissue comprise of

Answer 13

Widely spaced thin collagen fibres

Fibroblasts/fibrocytes

Unstained ground substances

Question 14

What does dense connective tissue comprise of

Answer 14

Closely spaced thick collagen fibres

Fibroblasts/fibrocytes

Unstained ground substance (less abundant than in loose connective tissue)

May be irregular or regular (running parallel to each other)

Question 15

What is the role of type 3 collagen - reticulin

Answer 15

Fibrillar collagen

Forms a supporting scaffold in many organs
- Bone marrow
- Liver/kidney
- Lymph node
- Spleen

Question 16

What stain must be used to see reticulin

Answer 16

Silver stain

Not visible on H&E

Question 17

What is elastin (elastic tissue)

Answer 17

Contains fine fibres and sheets of elastin

Elastin fibres may be branched

Produced by fibroblasts

Question 18

What colour is elastin stained on H&E

Answer 18

Pink

Question 19

What is white adipose (fatty) tissue

Answer 19

Large cells with single fat globule in each cell

Usually appear empty (white) in conventional slides as fat is extracted during process

Question 20

What is brown adipose (fatty) tissue

Answer 20

Cells with many globules of fat

Found across shoulders and down back of newborn

Important in neonatal thermo-regulation (generate heat to breakdown)

Question 21

What are the constituents of cartilage

Answer 21

Hard connective tissue

2 cell types
- chondroblasts
- chondrocytes

Set in abundant extracellular matrix

Extracellular fibres

Avascular - gets blood from blood vessels either side of cartilage

Question 22

What are the three types of cartilage

Answer 22

Hyaline cartilage

Question 23

What is hyaline cartilage

Answer 23

Found in synovial joints

Chondrocytes in lacunae surrounded by a glassy amorphous matrix

No visible fibres

Perichondrium - fibroblasts and collagen

Question 24

What is elastic cartilage

Answer 24

Visible elastic fibres

Perichondrium - fibroblasts and collagen

Chondrocytes trapped within matrix

Elastic fibres easily visible on H&E but clear on silver stain

Question 25

Where is elastic cartilage found

Answer 25

Pinna
Epiglottis

Question 26

What is fibrocartilage

Answer 26

Visible collagen fibres in matrix

Perichondrium - fibroblasts and collagen

Trapped chondrocytes

Question 27

Where is fibrocartilage found

Answer 27

Annulus fibrosus

Pubic symphysis

Question 28

What is synovium

Answer 28

Lines the inside of the joint capsule

1-4 layers of synovial fluid

Two types of cells -
Type A - phagocytes
Type B - rich in rER - secrete synovial fluid

Variable shapes - squamous to cuboidal

Richly vascular, highly innervated

Question 29

What are the three categories of muscle

Answer 29

Visceral (smooth) muscle

Voluntary (skeletal) muscle

Cardiac muscle

(other)

Question 30

What are visceral (smooth) muscle

Answer 30

Arterial wall
Wall of intestine
Airways of lungs

Question 31

What are voluntary (skeletal) muscle

Answer 31

Skeletal muscle
Larynx
Diaphragm

Question 32

What are cardiac muscle

Answer 32

Heart
Base of great vessels

Question 33

What fall under other muscle types

Answer 33

Pericytes
Myo-fibroblasts
Myo-epithelial cells

Question 34

What is smooth muscle

Answer 34

Involuntary muscle

Fusiform cells

Central nucleus

Non striations

Non-branching

Question 35

Describe the features of the dermis underneath the epidermis

Answer 35

Thick layer of dense irregular connective tissue

Consists of long fibres of collagen that run in many directions to form a mat-like fibrous scalp

Fibres stain dark pink

Have fibroblasts with dark blue nuclei lying alongside them

Question 36

What are tendons composed of

Answer 36

Thick ribbons of parallel collagen fibres

Between lie the fibroblasts which synthesis them

Question 37

Describe the composition of the penis

Answer 37

Contains mixture of loose and dense irregular fibrous connective tissue

Question 38

Describe the wall of arteries

Answer 38

Most contain a large amount of smooth muscle

Those close to the heart the muscle replaced by concentric sheets of elastic tissue

Sheets stain pink with eosin