Figure 2
From: Cell-to-cell signaling through light: just a ghost of chance?
Light emission phenomena in biological systems. Typical intensity of bioluminescence is significantly higher than weak photon emission of unspecific auto-luminescence (A). Typical setup for experiments dealing with cellular signaling through light is based on placing cell cultures to either Petri dishes, one put on the top of other (B), or inserted cuvettes (C).