lobulation

Lobulation is the organization or appearance of tissue into lobes or lobules, typically separated by connective tissue septa or by natural fissures. The term is used across anatomy, histology, radiology, and pathology to describe a pattern of structure rather than a single specific organ.

In anatomy and development, lobulation arises when developing tissue subdivides into discrete units. This pattern may persist into adulthood or reflect normal variation across species and organs. The presence of lobulation can influence the surface contour, internal architecture, or functional subdivision of an organ, depending on the tissue and context.

Common examples include the lungs, where the organ is divided into lobes by fissures (three lobes on the right and two on the left) and the parenchyma is organized into smaller lobules. In the liver, histological lobules form the functional units, grouped within larger lobes and segments. Placental lobulation refers to a lobed appearance of the placental surface. In some species or developmental stages, other organs such as the kidney or spleen may also exhibit lobulated contours.

In clinical imaging and pathology, lobulation describes a pattern rather than a specific diagnosis. A lobulated lesion on radiographs or other imaging modalities indicates a segmented or multi-part border and can be seen with a range of benign and malignant processes; the descriptor is non-specific and typically prompts further evaluation. Pathologically, lobulation denotes the arrangement of cells into lobules within glands or lymphoid tissue, often separated by fibrous stroma.

Overall, lobulation is a general descriptive term used to characterize tissue architecture that is divided into lobes or lobules across various organs and contexts.