serøs

Serøs (from Latin serum) is an adjective used in medicine and biology to describe fluids, membranes or secretions that are thin, watery and protein-poor, resembling serum. The term is common in anatomy and pathology to distinguish clear, non-purulent exudates or secretions from mucous, purulent or hemorrhagic types.

Serous membranes (serosae) line closed body cavities and cover internal organs; examples include the pleura, pericardium and peritoneum. These membranes produce serous fluid that lubricates organ surfaces and permits frictionless movement during respiration, digestion and cardiac activity. Serous glands, such as the acini of the parotid salivary gland, secrete watery, enzyme-rich fluid.

In pathology, serous effusion refers to accumulation of clear, straw-colored fluid in a cavity—pleural effusion, pericardial effusion and ascites can be serous. Serous inflammation is characterized by accumulation of protein-poor fluid, often in response to viral infections, burns or mild irritation. Cytological and biochemical analysis of serous fluid typically shows low protein concentration and relatively few inflammatory cells, aiding differential diagnosis from exudative or septic processes.

The adjective also appears in lesion names (e.g., serous cystadenoma, serous carcinoma), indicating tumors that produce or resemble serous secretions; ovarian serous carcinoma is a notable example. Recognition of serous characteristics assists clinicians and pathologists in diagnosis, management and prognosis.