Kõhrest

Kõhrest is a firm, flexible connective tissue that plays a central role in the skeletal system. It provides structural support, cushions joints, and forms templates for developing bones in the fetus and growing individuals.

There are three main cartilage types: hyaline, elastic, and fibrocartilage. Hyaline cartilage is the most widespread and consists mainly of type II collagen and proteoglycans; it covers articular surfaces and forms the ends of ribs. Elastic cartilage contains a dense network of elastic fibers and is found in the external ear and epiglottis. Fibrocartilage has thick collagen fibers and resists compression, occurring in intervertebral discs, the pubic symphysis, and knee menisci.

Cartilage is avascular and aneural; chondrocytes reside in lacunae within a gelatinous extracellular matrix. The tissue is typically surrounded by a perichondrium, except at articular surfaces. Nutrients reach chondrocytes by diffusion from surrounding synovial fluid or interstitial spaces, which also contributes to its limited capacity for repair.

Developmentally, cartilage forms during fetal growth and childhood through endochondral ossification and, in some sites, appositional growth from the perichondrium. Repair after injury is limited due to its avascular nature; damaged cartilage often heals slowly and may regenerate only partially, sometimes with scar tissue or fibrocartilage formation.

Clinically, degeneration or injury of articular cartilage is central to conditions such as osteoarthritis and various joint disorders. Treatments range from conservative approaches—physical therapy and anti-inflammatory medications—to surgical and regenerative strategies, including microfracture, autologous chondrocyte implantation, and cartilage grafts or engineered substitutes.