membranous

Membranous is an adjective describing anything related to membranes, thin sheets that separate, protect, or compartmentalize. In biology, membranes are typically lipid bilayers with embedded proteins, forming barriers around cells and organelles.

In cell biology, many structures are membranous organelles, such as the endoplasmic reticulum, Golgi apparatus, mitochondria, chloroplasts, lysosomes, and peroxisomes. These components are enclosed by membranes that define compartments and regulate transport and chemistry.

In development and pathology, membranous can describe processes like membranous ossification, where bone forms from fibrous membranes, as opposed to endochondral ossification. In medical conditions, membranous nephropathy is a nephrotic syndrome caused by immune complex deposition in the glomerular basement membrane, leading to thickened capillary walls. The term can also describe thickened or abnormally structured membranes in tissues.

Anatomically, membranes include mucous membranes lining cavities that open to the outside, serous membranes lining body cavities (pleura, peritoneum, pericardium), synovial membranes lining joints, and the cutaneous membrane (skin). These membranes provide lubrication, protection, and selective barriers.

In other fields, membranous can refer to thin film barriers in materials science or to membrane-like layers in various synthetic or natural systems.