hyaline cartilage

Examples of hyaline cartilage in the following topics:

• Cartilaginous Joints: Synchodroses

  • Cartilaginous joints are connected entirely by cartilage (fibrocartilage or hyaline).
  • Where the connecting medium is hyaline cartilage, a cartilaginous joint is termed a synchondrosis or primary cartilaginous joint.
  • In this example, the rib articulates with the sternum via the costal cartilage.
  • The epiphyseal plate is a hyaline cartilage plate in the metaphysis at each end of a long bone.
  • Section through occipitosphenoid synchondrosis of an infant, including the cartilage, perichrondrium, and periosteum.

• Bone Repair

  • The periosteal cells proximal (closest) to the fracture gap develop into chondroblasts that form hyaline cartilage.
  • The fibroblasts within the granulation tissue develop into chondroblasts that also form hyaline cartilage.
  • Eventually, the fracture gap is bridged by the hyaline cartilage and woven bone, restoring some of its original strength.
  • The next phase is the replacement of the hyaline cartilage and woven bone with lamellar bone.
  • Substitution of the woven bone with lamellar bone precedes the substitution of the hyaline cartilage with lamellar bone.

• Structure, Type, and Location of Cartilage

  • In the embryo, bones form first as hyaline cartilage before ossifying as development progresses.
  • Hyaline cartilage is found on many joint surfaces.
  • Elastic cartilage is histologically similar to hyaline cartilage but contains many yellow elastic fibers lying in a solid matrix.
  • Images of microscopic views of the different types of cartilage: elastic, hyaline, and fibrous.
  • Elastic cartilage has the most ECM; hyaline a middle amount; and fibrous cartilage has the least amount of ECM.

• Types of Connective Tissue

  • Cartilage is composed of specialized cells called chondroblasts and, unlike other connective tissues, cartilage does not contain blood vessels.
  • Cartilage is classified in three types: 1) elastic cartilage, 2) hyaline cartilage, and 3) fibrocartilage, which differ in the relative amounts of these three main components.
  • This is similar to hyaline cartilage but is more elastic in nature.
  • It is a major part of the embryonic skeleton, the costal cartilages of the ribs, and the cartilage of the nose, trachea, and larynx.
  • This is a blend of hyaline cartilage and dense regular connective tissue.

• Cartilage Growth

  • The division of cells within cartilage occurs very slowly.
  • Therefore, growth in cartilage is usually not based on an increase in size or mass of the cartilage itself.
  • Remodeling of cartilage is predominantly affected by changes and rearrangements of the collagen matrix, which responds to tensile and compressive forces experienced by the cartilage.
  • Damaged hyaline cartilage is usually replaced by fibrocartilage scar tissue.
  • However, due to the extremely slow growth of cartilage and its avascular properties, regeneration and growth of cartilage post-injury is still very slow.

• Development of Joints

  • Articular cartilage is a flexible material found between bones at movable joints.
  • Following the initial chondrification that occurs during embryogenesis, cartilage growth consists mostly of the maturing of immature cartilage to a more mature state.
  • The division of cells within cartilage occurs very slowly, and thus growth in cartilage is usually not based on an increase in size or mass of the cartilage itself.
  • Articular cartilage is maintained by embedded chondrocytes that comprise only 1% of the cartilage volume, and remodeling of cartilage is predominantly affected by changes and rearrangements of the collagen matrix, which responds to tensile and compressive forces experienced by the cartilage.
  • Histological image of the hyaline cartilage which coats the articular surfaces of joints.

• Postnatal Bone Growth

  • The diaphysis and both epiphyses of a long bone are separated by a growing zone of cartilage (the epiphyseal plate).
  • This process involves replacing the hyaline cartilage, initially present at the epiphyseal region, with active osteoblasts that deposit bone structural proteins.
  • Zone of reserve cartilage: This region is farthest from the marrow cavity and consists of hyaline cartilage that does not actively transform into bone.
  • Pictured is part of a longitudinal section of a rabbit's developing femur, with parts including: a) Flattened cartilage cells; b) Enlarged cartilage cells; c), d) Newly formed bone; e) Osteoblasts; f) Giant cells or osteoclasts; g), h) Shrunken cartilage cells.
  • Differentiate among the zones of development from cartilage to bone in postnatal ossification

• Trachea

  • At the top of the trachea and bottom of the larynx is the cricoid cartilage, the only complete ring of cartilage in the trachea.
  • The cartilage of the trachea is considered hyaline cartilage: simple, transparent, and made primarily of collagen.
  • The trachealis muscle connects the open ends of the C-shaped rings of cartilage and contracts during coughing, reducing the size of the lumen of the trachea to increase the air flow rate.
  • A cross section of the trachea, showing the hyaline cartilage, mucus glands, and ciliated epithelium.

• Structural Classification of Joints

  • Cartilaginous joints are connected by fibrocartilage or hyaline cartilage.
  • This diagram of a synovial joint delineates the articular cartilage, articular capsule, bone, synovial membrane, and joint cavity containing synovial fluid.
  • Image demonstrates a synchondrosis joint with epiphyseal plate (temporary hyaline cartilage joint) indicated (a) and a symphysis joint (b).

• Embryonic and Fetal Bone Formation

  • Unlike the other process of bone creation— endochondral ossification—intramembranous ossification does not involve cartilage.
  • Unlike intramembranous ossification, cartilage is present during endochondral ossification.
  • The osteoblasts secrete osteoid against the shaft of the cartilage model (appositional growth).