{{short description|Cavity within an organ}} thumb|right|Cross section of the gut. The lumen is the space in the middle also known as the volume. [[File:Normal breast histology.png|thumb|Normal histology of the breast, with ''lumen'' annotated at bottom right]] In biology, a '''lumen''' ({{plural form}}: '''lumina''') is the inside space of a tubular structure, such as an artery or intestine.<ref>Stedman's Medical Dictionary, 24th ed.</ref> It comes {{ety|la|lumen|an opening}}.
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<ref>{{cite book |last = Adds |first = John |author2 = Erica Larkcom |author3 = Ruth Miller |title = Exchange and transport, energy and ecosystems |year = 2004 |publisher = Nelson Advanced science (Nelson Thornes) |isbn = 0-7487-7487-4 |page = [https://archive.org/details/exchangetranspor0000adds/page/16 16] |url = https://archive.org/details/exchangetranspor0000adds/page/16 }}</ref> *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 *the fluid-filled cavity forming in the blastocyst during pre-implantation development called the blastocoel
In cell biology, '''lumen''' is a membrane-defined space that is found inside several organelles, cellular components, or structures, including thylakoid, endoplasmic reticulum, Golgi apparatus, lysosome, mitochondrion, and microtubule.
==Transluminal procedures== {{Anchor|transluminal}}''Transluminal procedures'' are procedures occurring through lumina, including:{{cn|date=April 2023}} *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
==See also== *Foramen, any anatomical opening
==References== {{Reflist}}
Category:Anatomy Category:Blood {{anatomy-stub}}