A microscopy-based approach for studying meiosis in live and fixed human oocytes

Human eggs frequently carry an incorrect number of chromosomes, which is a leading cause of pregnancy loss and congenital disorders. The origins of high aneuploidy rates in human eggs have remained largely unclear. This is due to two main reasons: first, the availability of human eggs is limited so that studies of fixed human eggs typically involve very small numbers and limited quantifications. Second, methods for studying meiosis in live human eggs have been missing. The ever rising prevalence of Assisted Reproductive Technologies has facilitated a recent breakthrough in the field. The mechanistic basis of meiosis in humans can now be examined directly in live eggs. Here, we present a robust method for culturing human eggs in vitro and describe how meiotic processes in human eggs can be studied in real time using fluorescent reporters. We further describe methods for the in-depth analysis of immunolabeled eggs by super-resolution light microscopy.