Bioluminescent endoscopy methods in which bioluminescent generating system components are combined ex vivo immediately prior to injection or infusion into a tissue area of interest to enable bioluminescent viewing of the tissue. The bioluminescent generating system components are combined by simultaneous injection into a Y tube or other in-line mixing chamber receiving fluid inputs from two or more fluid conduits and providing a fluid output to at least one fluid conduit. The mixed components which are the output of such multi lumen mixing system is injected into a hollow viscus organ or otherwise applied to organs and/or tissues of the body.