Cross section of the gut. The lumen is the space in the middle also known as the volume.
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'.
It can refer to:
In cell biology, a lumen is a membrane-defined space that is found inside several organelles, cellular components, or structures:
Transluminal procedures are procedures occurring through lumina, including: