Investigating How Active Fluid Flow Shapes Embryos

Humans and animals start as a simple biological system but develop into a complex organism. Qualitatively, we understand our development in great depth. While developmental biology has revealed molecular mechanisms governing the fate of cells, how organs get in shape remains an open question. Mechanical stress has been used in physics to bridge the gap between molecular level forces inside a material and its final shape. Here we aim to expand this concept towards understanding organ deformation using the fruit fly embryo as a model system. In contrast to inanimate matter, living systems consist of active agents that consume energy to perform work. The fruit fly is a standard subject of study in developmental research and we can genetically modify it to see its internal structure. We use a technique called Light Sheet Microscopy that allows for non-invasive recording of entire embryos in real time. Furthermore, we describe the fly’s development by approximating cells as parts of a ‘fluid’ of high internal friction. Using this approach, we identified when a primary cell layer expanded and contracted during embryogenesis and we recognized that this growth is largely due to cell activity. We believe that the study of fly development will help enrich our understanding of organ growth and eventually lead to the implementation of this knowledge in other biological systems of interest.