+A hollow organ is a body part, often tube-like or sac-like, designed to contain or transport substances. Its empty space, or [Lumen](/wiki/lumen), allows for vital bodily functions such as [Digestion](/wiki/digestion) and fluid storage. These structures are crucial for an organism's internal processes.
+## See also
+- [Organ System](/wiki/organ_system)
+- [Body Cavity](/wiki/body_cavity)
+- [Tissue](/wiki/tissue)