lumen (anatomy) lumen (anatomy) in biology, a lumen (plural lumina) is the inside space of a tubular structure, such as an artery or intestine. it comes from latin lumen 'an opening'. cross section of the gut. the lumen is the space in the middle also known as the volume. normal histology of the breast, with lumen annotated at bottom right. it can refer to: the interior of a vessel, such as the central space in an artery, vein or capillary through which blood flows. the interior of the gastrointestinal tract the pathways of the bronchi in the lungs the interior of renal tubules and urinary collecting ducts the pathways of the female genital tract, starting with a single pathway of the vagina, splitting up in two lumina in the uterus, both of which continue through the fallopian tubes in cell biology, a lumen is a membrane-defined space that is found inside several organelles, cellular components, or structures: thylakoid, endoplasmic reticulum, golgi apparatus, lysosome, mitochondrion, or microtubule transluminal procedures transluminal procedures are procedures occurring through lumina, including: natural orifice transluminal endoscopic surgery in the lumina of, for example, the stomach, vagina, bladder, or colon procedures through the lumina of blood vessels, such as various interventional radiology procedures: percutaneous transluminal angioplasty percutaneous transluminal commissurotomy