Light microscopy of mammalian gametes and embryos: methods and applications

In recent years, we have witnessed an unprecedented advancement of light microscopy techniques which has allowed us to better understand biological processes occurring during oogenesis and early embryonic development in mammals. In short, two modes of cellular imaging are now available: those involving fluorescent labels and those which are fluorophore-free. Fluorescence microscopy, in its various forms, is used predominantly in research, as it provides detailed information about cellular processes; however, it can involove an increased risk of photodamage. Fluorophore-free techniques provide, on the other hand, a smaller amount of biological data but they are safer for cells and therefore can be potentially used in a clinical setting. Here, we review various fluorescence and fluorophore-free visualisation approaches and discuss their applicability in developmental biology and reproductive medicine.