This ghostly picture, remeniscint of The Scream by Edvard Munch, is actually depicting the lung using a technique called immunofluorescence. This technique makes use of antibodies (the “immuno”) to detect specific cell types or cells making a certain protein. Antibodies are made by B cells to neutralize viruses and bacteria but they serve many uses in the laboratory. The antibody is connected to a colorful molecule that makes light (the “fluorescence”). In this picture the blue is simply a dye used to stain the nucleus of cells (the “organ” in a cell that contains all of the DNA….all cells in our bodies, except red blood cells, have a nucleus so all cells are stained with this dye). The green is an antibody that is supposed to detect macrophages although in this case the antibody is very sticky and most of the green you are seeing is just background and not really macrophages. The two large eyes at the top are bronchial epithelium (where lots of the mucous is made in the lungs) and the lower mouth is some sort of blood vessel. Happy October!