Cartilage

Question 1

name the locations of hyaline cartilage

Answer 1

• nose - cartilaginous portion
• tracheal and bronchial rings
• laryngeal cartilages
• costal cartilages
• articular surfaces of long bones
• epiphyseal growht plate
• fetal skeleton

Question 2

describe the perichondrium

Answer 2

• perichondrium (vascular) supplies cartilage (avascular) with nutrients
• 2 layers:
  
  • inner cellular layer:
    
    • source of chondroblasts
  • outer fibrous:
    
    • contains fibroblasts
    • type I collagen
    • blood vessels

Question 3

describe chondrocytes

Answer 3

• matured chondroblasts located in the lacunae of cartilage and are surrounded by matrix
• located superficially, chondroblasts are ovoid positioned so that their longitudinal axes lie parallel to the cartilage surface

Question 4

describe isogenous groups (cell nest)

Answer 4

• mitotic division of chondrocytes leads to a group of 4-8 chondrocytes, which is an isogenous group
• as chondrocytes in isogenous groups mature, they move apart by their own synthesis of ECM which lengthens the cartilage

Question 5

describe the capsular matrix

Answer 5

• capsular matrix is the matrix adjacent to the chondrocyte
  
  • poor in collagen but rich in GAGs
• stains deeply basophilic
• territorial matrix (TM): matrix found around isogenous groups
• interterritorial matrix (IM): matrix in between isogenous groups

Question 6

describe the matrix

Answer 6

• it is composed of amorphous ground substance and type II collagen fibrils
  
  • collagen constitutes about 40% of total matrix
• sulphated groups present in GAGs make it hydrophilic, enabling easy diffusion of nutrition to cells
• presence of proteoglycans provide immense strength to the matrix so that cartilage can function as a model for bone formation

Question 7

describe appositional growth

Answer 7

• occurs from chondrogenic cells in the perichondrium differentiating into chondroblasts, forming a new layer of cartilage around the periphery of the existing cartilage
• increases the width or thickness of cartilage

Question 8

describe interstitial growth

Answer 8

• occurs in young cartilage from cell divisions within the cartilage
• increases the length of the cartilage
• positive hormonal influence:
  
  • growth hormone
  • thyroxine
  • testosterone
• negative hormonal influence:
  
  • hydrocortisone
  • estradiol

Question 9

name locations of elastic cartilage

Answer 9

• pinna of the ear
• auditory canal
• eustachian tube
• epiglottis

Question 10

describe the matrix of elastic cartilage

Answer 10

• matrix is identical to that of hyaline cartilage, except it also contains a network of elastic fibers that impart to it a yellowish color
  
  • desmosines and isodesmosines
• ECM: type II collagen and elastic fibers

Question 11

name locations of fibrocartilage

Answer 11

• intervertebral disc
• pubic symphysis
• medial and lateral menisci
• attachment of ligament to bone

Question 12

describe the matrix of fibrocartilage

Answer 12

• contains type I mainly and type II collagen fibers
  
  • type I = trichrome stain
• GAGs = predominantly chondroitin and dermatan sulphates
• no perichondrium so only interstitial growth