A Luminescence of tibial cranial muscle and knee joint area after electrotransfer of a luciferase-encoding plasmid and i.p. injection of luciferin. Observation was done 26 minutes after i.p. injection of luciferin (2.5 mg/250 μl) and 7 days after electrotransfer of 3 μg and 60 μg of luciferase encoding plasmid (pC1-luc) into the tibial cranial muscle (on the left) and the knee joint (on the right) respectively. Levels of luminescence are represented in false colours according to a scale from 400 to 1500 (whole scale 65000). 1B and 1C Fluorescence of knee joint after injection of fluorescent albumin. Skin of the leg was removed. Fluorescence was induced with λex = 540 +/- 20 nm and observation was done at λem > 630 nm. Panel B: At these wavelengths, without injecting fluorochrome, it was possible to see bones by transparency. Panel C Just after injection, labelled albumin is concentrated within patella of the knee joint and some diffusion of fluorescence within the joint can be observed. Levels of fluorescence are represented in false colors.