Hyalinen

Hyaline describes a glassy, translucent appearance of certain tissues or substances in biology. The term derives from the Greek hyalos, meaning glass, and is used descriptively in histology and pathology rather than as a single tissue name.

Hyaline cartilage is the best-known example. It is a type of connective tissue found in joints, the nose, larynx, trachea, bronchi, and the developing fetal skeleton. Its extracellular matrix is rich in type II collagen, proteoglycans, and water, with chondrocytes housed in lacunae. The tissue is avascular and aneural; nutrients reach cells by diffusion from surrounding tissues and, at joints, from synovial fluid. Hyaline cartilage provides a smooth, low-friction surface and helps distribute mechanical loads.

Other hyaline-form tissues include hyaline membranes, which are thin, eosinophilic layers that line alveoli in certain lung conditions such as acute respiratory distress syndrome and neonatal respiratory distress syndrome. These membranes reflect protein- and cell debris-rich exudates that impair gas exchange.

Hyaline change and hyaline arteriolosclerosis describe deposition or transformation of tissue into a uniform, glassy appearance in various organs. Hyaline arteriolosclerosis, for example, involves thickening of small arteries by homogeneous protein deposits and is associated with aging, hypertension, and diabetes. Hyaline changes can also occur in glomeruli and other structures during chronic disease.

In pathology, the common thread is a translucent, glassy look on microscopic examination, which can occur in normal developmental contexts (as with cartilage) or as a result of disease processes involving protein deposition or edema.