Cartilage Histology Flashcards
What are the cells of cartilage?
Chondroblasts (“chondrocytes”) → maintain the matrix
Avascular
No nerve supply
Function of cartilage
Shock absorber
Bone growth
Fracture repair
Hyaline cartilage
Arthritis (joints, nasal, septum, airtube, ribs)
Elastic cartilage
Ear, nose
Fibrocartilage
Meniscus, intervertebral discs
May develop as result of hyaline cartilage damage
Perichondrium
Carries blood supply for avascular cartilage
Source of new cartilage cells
Perichondral cell types (carries blood supply and source of new cartilage cells)
- Fibrogenic cells: OUTER perichondrium, become fibroblasts → make fibers, ground substance
- Chondrogenic: INNER, give rise to chondroblasts (maintain matrix)
Chondroblasts (“chondrocytes”)
Maintain matrix
“flatter” cells with large nucleus
Chrondroclasts
Cartilage resorption
Remove calcified cartilage
Matrix has what in it?
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)
What is given to treat osteoarthritis?
Hylauronic acid or Hylauron
Also used as lip filler in plastic surgery
What nourishes the hyaline cartilage?
Perichondrium
How is Hyaline cartilage growth stimulated?
By hormones: Somatotropin, thyroxine, testosterone
Matrix formation and growth inhibited by: cortisone, hydrocortisone, estradiol
Vit A deficiency does what to cartilage?
Retards growth, reduces width of epiphyseal plate, inhibits matrix synthesis → scurvy
Vit D deficiency does what to cartilage?
Chondrocytes proliferate but the matrix doesn’t calcify properly → RICKETS
(Rickets: not enough sun and breast feeding)
Fibrocartilage
No perichondrium
Chondrocytes in rows (they maintain matrix)
Appositional Cartilage Growth
Forms new cartilage on top of pre-existing cartilage (inner layer of perichondrium)
After growth initiated, cells become chondroblasts/chondrocytes
Interstitial Cartilage Growth
Takes place within cartilage mass itself
Chondrocytes divide, secrete new matrix
Limited by avascular nature
How is Cartilage Repair carried out?
Via the perichondrium
More common during growth
Adults have few chondrocytes
Cartilage is usually replaced by dense connective tissue or bone (if vascularized)
Cranial synostosis
Bone growth instead of cartilage repair (high oxygen tension produces osteoblasts)
Articular cartilage
Hyaline cartilage
Reduces friction between bones
No nerves or blood vessels
Nourished by synovial fluid
No perichondrium (hyaline cartilage usually has perichondrium)
What does the Articular Capsule do?
Ligaments help limit joint movement
Synovial membrane
Lines entire joint cavity (except articular cartilage that is on bones)
Makes synovial fluid
Vascularized
