Histology/Pathology

Question 1

Where do we see:

• Hyaline cartilage
• Elastic cartilage
• Fibrocartilage

Answer 1

• Joints
• Ears
• IV discs

Question 2

What is the structure of compact bone?

Answer 2

Concentric layers

haversian systems

Question 3

What are sharpey’s fibres?

Answer 3

Collage type 1 from tendons running into bone at their insertion

Question 4

In terms of osteoclasts:

• How many nuclei
• Origin
• Secretion product and role? What other cell does this too?

Answer 4

• Multi nucleated
• granulocytes/macrophage origin
• HCl and proteases to remodel bone and increase blood calcium.
  Osteocytes can also increase blood calcium

Question 5

What is the sequence of cartilage replacement with bone?

Answer 5

• Bone forms first around diaphysis to starve underlying cartilage.
• it dies and blood vessels invade bringing in bone cell progenitors
• 2nd COF in epiphysis
• keep growth plate until around 21

Question 6

What is the structure of new bone or repaired bone and how is it remodelled?

Answer 6

Woven bone with collagen in interlacing bundles.
Remodelled into haversian systems
- Osteoclasts tig tunnels into the bone in the right shape.
- Oteoblast line them and create alternating rings of bone to make the haversian system with a canal in the middle

Question 7

What is the origin of flat bones?

Answer 7

Intramembranous ossification

- Mesenchymal stem cells become osteoprogenitor cells which just start secreting osteoid

Question 8

What is in osteoid?

Answer 8

Collagen type 1
Proteins and a few GAGs
Cytokines and GF
Enzymes such as alkaline phosphatase

Question 9

What are the 3 phases of fracture healing?

Answer 9

1. Inflammation; haematoma formation (osteoblasts, chondrocytes and fibroblasts depending on stability) and granulation tissue
2. Reparative phase; soft callus (cartilage with periosteum repairing on outside) and hard callus (woven)
3. Remodelling phase (lamellar)

Question 10

What is the clinical management of a fracture?

What can be some complications?

Answer 10

Reduction and fixation, and minimise any risk factors that slow healing. 
Non union leading to pseudo arthritis
Mal-union
Osteomyelitis 
Osteonecrosis

Question 11

What % of bone is remodelled each year?

Which bone is usually affected by processes that affect remodelling?

Answer 11

10%

Trabecular bone- more metabolically active and larger SA. e.g. in vertebral bodies and femoral neck

Question 12

What are the components of hyaline cartilage?

Answer 12

Collagen type 2
WATER!
proteoglycans
chondrocytes (which secrete the matrix)

Question 13

Why isn’t synovium an epithelium? What does it allow to pass? what cells make it up?

Answer 13

No basement membrane
allows plasma filtrate through
macrophage like cells and fibroblast like cells

Question 14

What might we see histologically in osteoarthritis?

Answer 14

• Loss of cartilage
• Subchondral thickening (may see cysts there too)
• Osteophytes

Question 15

What type of disease is rheumatoid arthritis? what would you see histologically?

Answer 15

Autoimmune systemic inflammatory

• Mononuclear infiltrate and germinal centres
• Synovial hyperplasia and villus formation
• Pannus; invading and eroding bone and cartilage

Question 16

Compare OA and RA clinical symptoms

Answer 16

OA not systemic just in a few joints
RA systemic
OA; deep achy pain with decreased ROM. worse after movement.
RA; warm and swollen, decreased ROM and bad in morning, eases on activity.
OA can see osteophytes, RA can see deformities

Question 17

What is the pathology of gout?

What can it progress to if untreated?

Answer 17

Uric acid crystals deposit causing inflammatory cascade

Depositions of tophi

Question 18

What type of inflammation occurs in gout? what would you see histologically in a tophi?

Answer 18

granulomatous

see multinucleate giant cells and epitheliod macrophages around urate crystals