11. Histology of Bone & Cartilage

Question 1

Label this (bone).

Answer 1

Question 2

What are the 2 types of bone?

• Other names for lamellar bone?
• Other names for woven bone?
• Where do each lie in a bone?
• Functions of each?

Answer 2

Types of Bone

Lamellar Bone (80% skeletal weight)

• Also known as Cortical, Compact, or Dense bone
• Weight bearing tissue of long bones
• Mature

Woven Bone

• Also known as Cancellous, Trabecular or Spongy bone
• Supportive, scaffolding structure of inner bone
• In healing bone is the immature precursor

Question 3

What are the 4 cells of bone?

• What is the embryological origin of Osteoprogenitor cells?

Answer 3

Question 4

Label the bone cells here.

Answer 4

Question 5

Label the components of bone.

Answer 5

Question 6

What is the Bone Matrix composed of?

Answer 6

Bone Matrix Composition

• Inorganic/Mineral component
  
  • 60 to 70% mineralized component
  • Microcrystalline calcium phosphate (hydroxyapatite)
  • Traces of sodium, magnesium, fluoride etc.
• Organic component
  
  • Type I collagen
  • Glycosaminoglycans

Question 7

What are 5 functions of bone?

Answer 7

Bone Functions

1. Support
2. Protection
3. Locomotion (with muscles)
4. Haematopoiesis (bone marrow)
5. Calcium and phosphorus storage

Question 8

How does bone develop?

Answer 8

Bone Development

• In the embryo formed from a cartilaginous precursor (most long bones)
• Precursor - osteoid - replaced by mineralized bone as it grows and is vascularized

Question 9

What are osteoids?

Answer 9

Question 10

What is Lamellar/Compact/Cortical/Dense Bone?

• What is their unit of structure?
• What surrounds it?
• What lines marrow cavity?

Answer 10

Lamellar/Cortical/Compact/Dense Bone

• Structure from transformation of osteoid
• Collagen aligned into sheets of parallel fibrils
• Composed of cylinders (along the long axis) known as osteons or Haversian systems
• Outside surrounded by circumferential lamellae and then periosteum
• Endosteum lines marrow cavity

Question 11

Describe the osteon of lamellar bone.

Answer 11

Osteon of Lamellar Bone

• Layered cylinders of collagen
• Lacunae of osteocytes between each layer(lamella)
• Canaliculae radiate from each lacuna and house osteocyte cellular processes
• Central - Haversian canal contains neurovascular components

Question 12

Label this image of bone.

Answer 12

Question 13

Answer 13

Question 14

Which cells can be seen here residing in the canaliculi of cortical bone?

Answer 14

Question 15

What do osteocytes look like at different life stages?

Answer 15

Question 16

What is Woven/Spongy/Cancellous/Trabecular Bone?

• Where is it found?
• What is it oriented to?
• What is it lined by?

Answer 16

Woven (Spongy, Cancellous, Trabecular) Bone

Within core of long bones

Collagen runs in various directions

Oriented to mechanical loads & stresses acting on the bone

Lined by osteoblasts

Question 17

Where is the lamellar bone?

Where is the cancellous bone?

Answer 17

Question 18

How old is this bone?

How can you tell?

Answer 18

Question 19

What kind of bone is this?

Answer 19

Question 20

What is Cartilage?

• Can it regenerate?
• Blood supply?
• Where does it receive its nutrients from?

What is happening at the mark pointed to by the arrow?

• What part of bone does it form?

Answer 20

Cartiliage = CT

• Does not regenerate
• Is avascular (no blood supply)
• Nutrients by diffusion from perichondrium & synovial fluid
• Forms the bone growth plate
  – Also known as the epiphyseal plate

Question 21

Label this.

Answer 21

Question 22

What are 3 functions of cartilage?

Answer 22

Cartilage Functions

1. Frictionless surface for smooth movement
2. Shock absorption - Deformable gel (80% water)
3. Resists mechanical stress

Question 23

What is the Structure of Cartilage (Cells & Matrix)?

Answer 23

Cartilage Structure

Cells

1. Chondroblasts - Derived from mesenchymal chondrogenic cells of the perichondrium
2. Chondrocytes - Sit in their own lacunae, arranged according to type of cartilage & Secrete cartilage matrix
3. Perichondrium
   • Capsule of mesenchymal cells
   • Vascular supply which feeds cartilage

Matrix (gel-like)

• Glycosaminoglycans (GAGs)
• Hyaluronic acid, chondroitin & keratan sulphates which are aggregated with collagen fibrils
• Proteoglycans
• Collagen (some water-bound here too)
• Hydrated (between 60 to 78% water) bound to negatively charged GAGs

Question 24

Describe the zones of cartilage growth.

Answer 24

Question 25

What are the 3 types of cartilage?

• What type of collagen are each composed of?
• Which is strongest?
• Where are they each found?
• Macroscopic/Microscopic appearances?
• Presence of perichondrium?

Answer 25

Types of Cartilage

1 - Hyaline (means glassy) = Type II collagen

2 - Elastic - more pliable = Type II collagen + Elastin

3 - Fibrocartilage - withstands strong tensile forces = Type I collagen = Structured array of collagen and chondrocytes

Question 26

Label this.

Answer 26

Question 27

What type of cartilage is this?

Answer 27

Question 28

What kind of cartilage is this?

Answer 28

= Fibrocartilage

Question 29

What are Joints?

• What are the 3 types of joints classified by structure and function?
• What is the binding material of each joint type?
• Which of these joints has a cavity?
• Examples of each

Answer 29

Joints

• Defined as connections between any rigid component parts in the skeleton
• Three types (structural classification)

1. Fibrous = Synarthoroses (immovable)
2. Cartilaginous = Amphiarthoroses (slightly movable)
3. Synovial = Diarthoses (freely moveable)

Question 30

Label this.

Answer 30

Question 31

Which type of cartilage forms intevertebral discs?

Answer 31

Question 32

What are the features of a Synovial joint?

Answer 32

Synovial Joint

• Cartilage/mineralized cartilage/subchondral bone
• Synovial Membrane(synoviocytes)
• Synovial fluid
• Peri-chondrium or peri-osteum
• Joint Capsule

Question 33

Label this.

Answer 33