At SLU in Uppsala, Sweden’s only in vitro embryo production laboratory for agricultural animals is located. The laboratory is well-equipped and has functional embryo production protocols for cattle and pigs. However, just like in the rest of the world, there is a lack of objective evaluation methods for the actual quality of oocytes and embryos in large parts. Objective evaluations of embryos and oocytes will improve our ability to select the oocytes and embryos best suited for transfer to recipient animals and may provide a better opportunity to transport frozen embryos instead of live animals, which is important for preventing disease spread and also beneficial for the preservation of endangered breeds. One of the cell organelles that is of great importance for the quality of oocytes and embryos is the mitochondria. These serve as energy producers and drive many of the processes in the oocyte and embryo. There is a lack of objective assessment methods for mitochondria in oocytes and embryos, something that would truly enhance our understanding of the developmental potential and hence the quality of the embryo/oocyte. Through previous experiments, protocols for staining and evaluation of lipids and cell nuclei in cattle embryos are now available, but further studies are needed to obtain a better picture of other important structures. This project aim to develop robust objective methods to evaluate mitochondria in bovine embryos.