Cartilage Histology

Question 1

What are the cells of cartilage?

Answer 1

Chondroblasts (“chondrocytes”) → maintain the matrix

Avascular

No nerve supply

Question 2

Function of cartilage

Answer 2

Shock absorber
Bone growth
Fracture repair

Question 3

Hyaline cartilage

Answer 3

Arthritis (joints, nasal, septum, airtube, ribs)

Question 4

Elastic cartilage

Answer 4

Ear, nose

Question 5

Fibrocartilage

Answer 5

Meniscus, intervertebral discs

May develop as result of hyaline cartilage damage

Question 6

Perichondrium

Answer 6

Carries blood supply for avascular cartilage

Source of new cartilage cells

Question 7

Perichondral cell types (carries blood supply and source of new cartilage cells)

Answer 7

1. Fibrogenic cells: OUTER perichondrium, become fibroblasts → make fibers, ground substance
2. Chondrogenic: INNER, give rise to chondroblasts (maintain matrix)

Question 8

Chondroblasts (“chondrocytes”)

Answer 8

Maintain matrix

“flatter” cells with large nucleus

Question 9

Chrondroclasts

Answer 9

Cartilage resorption

Remove calcified cartilage

Question 10

Matrix has what in it?

Answer 10

Proteoglycans (core proteins with GAG side chains)

Aggrecan=most abundant monomer

(gel-like consistency because: electrostatic bonds between GAG side chains, water binding to GAGs)

Question 11

What is given to treat osteoarthritis?

Answer 11

Hylauronic acid or Hylauron

Also used as lip filler in plastic surgery

Question 12

What nourishes the hyaline cartilage?

Answer 12

Perichondrium

Question 13

How is Hyaline cartilage growth stimulated?

Answer 13

By hormones: Somatotropin, thyroxine, testosterone

Matrix formation and growth inhibited by: cortisone, hydrocortisone, estradiol

Question 14

Vit A deficiency does what to cartilage?

Answer 14

Retards growth, reduces width of epiphyseal plate, inhibits matrix synthesis → scurvy

Question 15

Vit D deficiency does what to cartilage?

Answer 15

Chondrocytes proliferate but the matrix doesn’t calcify properly → RICKETS

(Rickets: not enough sun and breast feeding)

Question 16

Fibrocartilage

Answer 16

No perichondrium

Chondrocytes in rows (they maintain matrix)

Question 17

Appositional Cartilage Growth

Answer 17

Forms new cartilage on top of pre-existing cartilage (inner layer of perichondrium)

After growth initiated, cells become chondroblasts/chondrocytes

Question 18

Interstitial Cartilage Growth

Answer 18

Takes place within cartilage mass itself

Chondrocytes divide, secrete new matrix

Limited by avascular nature

Question 19

How is Cartilage Repair carried out?

Answer 19

Via the perichondrium

More common during growth

Adults have few chondrocytes

Cartilage is usually replaced by dense connective tissue or bone (if vascularized)

Question 20

Cranial synostosis

Answer 20

Bone growth instead of cartilage repair (high oxygen tension produces osteoblasts)

Question 21

Articular cartilage

Answer 21

Hyaline cartilage

Reduces friction between bones

No nerves or blood vessels

Nourished by synovial fluid

No perichondrium (hyaline cartilage usually has perichondrium)

Question 22

What does the Articular Capsule do?

Answer 22

Ligaments help limit joint movement

Question 23

Synovial membrane

Answer 23

Lines entire joint cavity (except articular cartilage that is on bones)

Makes synovial fluid

Vascularized