Cartilaginous Tissue Overview

Cartilaginous Tissue

• Specialized connective tissue
• Main cells are chondrocytes, occupying small cavities called lacunae in the matrix
• Matrix is firm but flexible, resistant to mechanical forces
• Matrix composed of GAGs, proteoglycans, type II collagen fibers, and sometimes elastic fibers
• Avascular tissue, cells nourished by diffusion through the matrix
• Large pieces of cartilage have channels for blood vessels and nerves
• Surrounded by perichondrium, a connective tissue sheath
• Perichondrium has two layers: outer fibrous (collagen type I, fibroblasts, vascularized) and inner cellular (chondroblasts that secrete matrix)
• Chondrocytes are responsible for secreting matrix
• Lacunae (small cavities) house chondrocytes
• Chondrocytes form groups within the same lacunae, called isogenic groups
• Interstitial growth arises from chondrocytes' division and secretion of matrix within the lacunae
• Cells grow in different compartments and increase the size and volume of the tissue

Formation of Cartilage

• During embryonic development, mesenchymal stem cells retract their extensions and group together, forming chondrification centers
• Under the influence of stimuli, these cells differentiate into chondroblasts
• Chondroblasts secrete matrix, then transform into chondrocytes when surrounded by matrix
• Chondrocytes retain their ability to divide
• Can form isogenic groups (groups of cells within same lacuna)
• When cells secrete matrix, they separate, making the cartilage grow from within (interstitial growth)

Types of Cartilage

• Hyaline cartilage: most abundant type, flexible, semi-translucent, bluish-gray color, uniform, resistant to tensile/compression forces

  • Precursor to long bones in embryonic development
  • Found in nasal cartilages, larynx, trachea/bronchi, ribs, and articular surfaces

• Elastic cartilage: similar to hyaline, but contains abundant elastic fibers, very flexible, yellowish color, more opaque compared to hyaline

  • Found in the external ear, auditory tubes, epiglottis, and parts of the larynx

• Fibrocartilage: intermediate between cartilage and dense CT, contains more type I collagen, has scarce matrix, less water and proteoglycans, and great tensile strength

  • Has chondrocytes aligned in parallel rows
  • Found in intervertebral discs, tendons/ligaments, and the pubic symphysis

Cartilage Growth

• Interstitial growth: chondrocytes divide within cartilage and secrete new matrix, expanding cartilage from within
• Apositional growth: new chondrocytes are formed from the perichondrium, an outer connective tissue layer
  • It adds cartilage layers to the outside, increasing cartilage thickness

Explore the essential characteristics of cartilaginous tissue in this quiz. Learn about chondrocytes, their role, and the unique structure of the matrix. Test your knowledge on the growth types and the surrounding perichondrium.