MSK histology

Question 1

What cells are found in cartilage?

Answer 1

Chondrocytes

Question 2

What are immature chondrocytes called?

Answer 2

Chondroblasts

Question 3

Where in the cartilage are chondrocytes found?

Answer 3

Within a space in the extracellular matrix, called a lacuna

Question 4

What is the function of a chondrocyte?

Answer 4

Secretion and maintenance of extra-cellular matrix

Question 5

What is the makeup of extra-cellular matrix of cartilage?

Answer 5

75% water
15% Type II collagen
10% Proteoglycan aggregates

Question 6

How does type II collagen differ from type I (Found in tendons)?

Answer 6

It is finer and forms a 3D meshwork instead of linear bundles

Question 7

What makes up the proteoglycan aggregates found in the extracellular matrix?

Answer 7

GAGS (Keratan sulfate and chondroitin sulfate) bound to a core protein and linked to hyaluronan

Question 8

Describe the histology of hyaline cartilage

Answer 8

The chondrocytes are flat near the perichondreum and rounded in deeper tissue, often in pair forming cell nests (Isogenous cell groups)

Question 9

What type of cartilage is shown here?

Answer 9

Hyaline cartilage

Question 10

Describe the histology of elastic cartilage

Answer 10

Elastic cartilage contains typical chondrocytes

Its matrix is pervaded by yellow elastic fibres, except around the lacunae

Its elastic fibres are irregularly contoured and show no periodic banding

Question 11

What are some special features of elastic cartilage?

Answer 11

Elastic cartilage is resistant to degradation and can regenerate to a limited degree following traumatic injury

Question 12

What type of cartilage is shown here?

Answer 12

Elastic cartilage

Question 13

Describe the histology of fibrocartilage

Answer 13

Fibrocartilage is dense and fasiculated, containing chondrocytes either singly or in isogenous groups, arranged into long rows, separated by coarse collagen type I fibres

It usually contains fibroblasts

The cells are ovoid and surrounded by concentrically striated matrix

Question 14

What are the 4 main components of bone?

Answer 14

• Bioapatite (65%)
• Collagen (23%)
• Water (10%)
• Non-collagen protein (2%)

Question 15

What is bioapatite?

Answer 15

Bioapatite is a form of calcium phosphate, mostly in the form of hydroxyapatite

Question 16

What are the 2 types of bone?

Answer 16

• Cortical bone - outer shell - makes up diaphysis
• Trabecular bone - Inner meshwork - Makes up epiphysis

Question 17

What are the main structural units of bone?

Answer 17

Osteons

Question 18

What are osteons?

Answer 18

Circular rings of interstitial lamellae, which surround a Haversian canal, containing an osteonal artery and nerve

Question 19

What forms the interstitial lamellae of bone?

Answer 19

Collagen fibres

Question 20

What are the connecting canal s between Haversian canals called?

Answer 20

Volkmann’s cannals

Question 21

What types of cells are found within bone?

Answer 21

• Osteoprogenitor cells
• Osteoblasts
• Osteocytes
• Osteoclasts

Question 22

What is the function of osteoprogenitor cells?

Answer 22

Osteoprogenitor cells are located on the bony surface and serve as a pool of reserve osteoblasts

Question 23

What are osteoblasts?

Answer 23

Osteoblasts are bone forming cells which are found on the surface of developing bone, containing many RER and mitochondria

Question 24

What is the function of osteoblasts?

Answer 24

They secrete collagen, GAGs and other components of the matrix, which is collectively known as osteoid, which becomes mineralised over time

Question 25

Where are osteocytes found?

Answer 25

Trapped within the bone matrix

Question 26

What are osteoclasts?

Answer 26

Osteoclasts are large multinucleate cells which are responsible for bone resorption

Question 27

What is osteoid?

Answer 27

A mixture of collagen, GAGs and other matrix compounds which mineralise to form bone