Abstract
Abstract in English, Portuguese In a previous paper, we showed a new giant lens called the Mesolens and presented performance data and images from whole fixed and intact fluorescently-stained 12.5-day old mouse embryos. Here, we show that using the Mesolens we can image an entire Drosophila larva or adult fly in confocal epifluorescence and show subcellular detail in all tissues. By taking several hundreds of optical sections through the entire volume of the specimen, we show cells and nuclear details within the gut, brain, salivary glands and reproductive system that normally require dissection for study. Organs are imaged in situ in correct 3D arrangement. Imaginal discs are imaged in mature larvae and it proved possible to image pachytene chromosomes in cells within ovarian follicles in intact female flies. Methods for fixing, staining and clearing are given. The fruit fly (Drosophila melanogaster) is one of the most important and widely studied model organisms in cell biology, and has been used to investigate organ development, neurobiology, and a range of human genetic diseases and conditions. However, at a few mm long, both larvae and adult flies are too large to be studied with conventional microscopes, and although macrophotography can accommodate the whole specimen, this method is low resolution and cannot capture cellular or sub‐cellular information. We have developed a new giant lens called the Mesolens that can image specimens several mm long with subcellular resolution in 3D. This report demonstrates the utility of the Mesolens for imaging whole late‐stage larvae and adult Drosophila flies. Using fluorescent dyes to label different parts of each cell in the organism, we have used the Mesolens to take several hundred images at different depths through the entire volume of the larva and fly specimens and we show cells and nuclear details within the gut, brain, salivary glands and reproductive system that normally require dissection for study. Organs are imaged in situ in their correct 3D arrangement. Using common freely available software, we have digitally reconstructed the whole adult fly in 3D, and, simply by a software zoom, we can look at individual cell nuclei and their relative positions inside the whole insect. We hope that this new imaging method will be of useful to the many thousands of cell biologists working with Drosophila.