The Greater Omentum: A Proposed Mechanism of Movement in the Abdomen.

The greater omentum is a thin sheet-like abdominal organ sandwiched between the anterior abdominal wall and the intestines. It possesses adipose deposits, an epiploic vascular system, arcade-like vascular loops, and a significant number of omental milky spots, the name given to the immune/lymphatic cell clusters residing in its tissues. Observational and experimental evidence confirms that the omentum moves toward inflamed abdominal organs and surgical sites and invades via vascular and fibrous tissues, in order to isolate the area and launch an immune response. Correlated to this, direct evidence of omental growth in response to inflammatory chemokine stimuli has also been established. Further, it has been demonstrated that the metabolic activity of the milky spots, when engaged in such a response, increases 10-20 fold, along with increases in the number and size of the spots. A mechanism of chemotaxis has yet to be identified, but it is clear that the omentum is an important immunological organ that responds to inflammation and infection in the abdomen, both cellularly and physically. We propose that the blood vessels of the omentum act as a multi-pronged hydrostat system, engorging themselves and their capillaries with blood, responding to an inflammatory trigger like inflated fire hoses, and extending the organ across the abdomen. Thus, the omentum represents an unique mobile immune system that we believe warrants further focus in anatomical, clinical, immunological, and biomechanical research.