Figure 2: Mechanism responsible for visibility of the white zone when viewed perpendicularly above the epithelium. Black arrows A and B represent NBI light. As the mucosa is semi-translucent, A-NBI light passing through intervening part of the epithelium is absorbed by the hemoglobin of red blood cells in blood vessels. As a result, the blood vessels appear as brown lines, as seen in Figure 2(b)A. However, B-NBI light passing into the epithelia of crypts is scattered before it reaches any blood vessels, and thus this area appears as a white zone, as seen in Figure 2(b)B. Intervening part means the protruding area between crypts (a). In images obtained by magnifying endoscopy with NBI, this corresponds to space between two white zones forming the mucosal pattern, including the white zones themselves (b).