Gabriella Sterne, Graduate Student (Ye Laboratory), Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan 

The common fruit fly, Drosophila melanogaster, is an important biological model for scientific study, Drosophila biologists have created genetically altered fly lines in which specific cell types are labeled; these lines allow the scientists to study specific cellular processes. This image comes from a genetic screen to find labeled cell populations in the region of the fly brain that is most similar to the human cerebrum (the fly doesn't really have a cerebrum like humans do). The pink stained cells are neurons that are parts of the two lobes of the fly protocerebrum and their projections link the two lobes. This region of the fly brain has been shown to be important in male mating behavior. As for what's under the bridges--who knows? We are still working on characterizing these lines, and there is much more to learn from them.