Knorpelhisto

Knorpelhisto is a term used in German-language anatomy and histology to denote the study of cartilage tissue at the microscopic level. It covers the normal structure, composition, development and pathology of cartilage, as well as the methods used to analyze it in tissue sections.

Cartilage tissue consists of specialized cells called chondrocytes embedded in an extracellular matrix rich in collagen type II, proteoglycans such as aggrecan, and high water content. Chondrocytes occupy lacunae and are organized within a pericellular, territorial, and interterritorial matrix. Cartilage is avascular and aneural in most regions; nutrients reach chondrocytes mainly by diffusion from surrounding tissues and synovial fluid, a factor that influences its growth and repair.

There are three main cartilage types: hyaline, elastic, and fibrocartilage. Hyaline cartilage is the most widespread and forms articular surfaces, the tracheal rings, and the growth plates. Elastic cartilage contains elastic fibers and is found in the external ear and epiglottis. Fibrocartilage has densely packed collagen fibers and is seen in intervertebral discs and the menisci. The articular cartilage layer of joints displays distinct zones (superficial, middle, deep, and calcified) and a tidemark separating non-calcified from calcified cartilage.

Knorpelhisto also covers development and growth. Cartilage originates from mesenchymal condensations and undergoes endochondral ossification in many bones, with growth occurring by both appositional and interstitial mechanisms. Histological techniques, including H&E, Safranin O staining, and immunohistochemistry for collagen type II and aggrecan, are used to study cartilage structure and pathology.

Clinical relevance includes osteoarthritis, chondrodysplasias, and approaches to cartilage repair and regeneration, such as microfracture, autologous chondrocyte implantation, and tissue engineering.