Histo - Cartilage

Question 1

What makes up Cartilage?

Answer 1

Basics:

• Chondrocytes = Cartilage cells
  
  • LM = seen in lacunae (artifact)
• Cartilage - specific ECM
  
  • specific to type of cartilage
    
    • Territorial = around isogenous groups (cell clusters)
    • Inter-territorial matrix = between isogenous groups
  • Proteoglycan = aggregated
  • Fibers differ

Characteristics:

• Special connective tissue
• Avascular
• Low proliferation levels
• May have perichondrium surrounding it

Functions:

• Line a surface (joints)
• Provide support (respiratory systems & bronchi)
• Transitional & connect 2 structures (fibrocartilage)
  
  • IVD
  • Sternoclavicular joint

Question 2

What are the 3 Types of Cartilage?

Answer 2

1. Hyaline
2. Elastic
3. Fibrocartilage

Question 3

How does Cartilage Grow?

Answer 3

Basics:

• Chondroblasts from perichondrium –> Chondrocytes
  
  • Appositional growth
  • Outside –> In
    
    • Mesenchymal cells/Fibroblasts –> Chondroblasts –> Chondrocytes
    • Chondroblast produce cartilage specific matrix
      
      • Type II Collagen
      • become surrounded = chondrocyte
• Chondrocyte division w/in cartilage matrix
  
  • Interstitial
  • Inside –> Out
    
    • Chondrocytes divide
      
      • form isogenous groups
    • Matrix surrounds = (darker stain)
    • Matrix in btw = (lighter stain)

Note:

• Unlike osteocytes, chondrocytes = proliferative

Question 4

What kind of growth is this?

Answer 4

Appositional Growth

Question 5

What type of growth is this?

Answer 5

Interstitial Growth

Question 6

What Extracellular Matrix is in Cartilage?

Answer 6

All Cartilage:

• Aggregated Proteoglycans (PGs)
  
  • PG: Core protein = AGGRECAN
    
    • chondroitin sulfate
    • keratan sulfate
  • PG: Hyaluronic acid
    
    • no sulfate/no core protein
    • interconnects the 2

Specific Types of Cartilage:

• Collage Type I
  
  • Fibrocartilage
• Collage Type II
  
  • Hyaline cartilage
  • Elastic cartilage
• Elastic fibers
  
  • Elastic cartilage
  • Type II collagen as well!

Question 7

What is this?

Answer 7

Hyaline Cartilage (trachea)

• Location = articular surfaces
  
  • walls of respiratory passages
  • epiphyseal plates

Characteristics:

• Appears glassy
• Discrete areas (w/perichondrium) or lining a joint (no perichondrium)
• Aggregated PG in matrix
• Circular isogenous groups
• Forms cartilage model for formation of long bones

Question 8

What are the components of Endochondral Ossification?

Answer 8

Note:

• Articular Cartilage has no Perichondrium

Question 9

What is this?

Answer 9

Hyaline Cartilagein an Extrapulmonary Bronchus

Question 10

What is this?

Answer 10

Elastic Cartilage in the Epiglottis

• Location = External ear, epiglottis, auditory tbe, corniculat cartilage of the larynx

Characteristics:

• Matrix = fiberous
• Discrete areas
• Type II collagen in matrix
• Aggregated PGs in matrix
• Circular isogenous groups
• Elastic fibers in matrix
• Perichondrium

Question 11

What is this?

Answer 11

Fibrocartilage (w/ Analine Blue stain)

• Location: IVD, articular disc of knee, sternoclavicular join, public symphysis

Characteristics:

• Transitional, merging w tendons, ligaments or hyaline cartilage
• NOT discrete areas
• Matrix = collagenous (dense regular CT)
  
  • Type I Collagen
• Aggregated PGs in matrix
• LINEAR isogenous groups
• NO perichondrium
  
  • ​NO appositional growth!

Question 13

What is this?

Answer 13

Fibrocartilage w/ H&E stain

Question 14

Summarize Cartilage Characteristics

Answer 14

Question 15

What is Osteoarthritis?

Answer 15

Basics:

• Despite its name, it is a disease of CARTILAGE

Symptoms:

• Pain
• Stiffness
• Loss of mobility

Pathology:

• Cartilage Lost
  
  • Ex:
    
    • on Femur Head
    • at joints (loss of joint space)