Isolating Single Cells from Xenopus Early Embryos and Sorting Them by Size

Early embryogenesis requires an exponential decrease in cell size, while the embryo remains constant in size at the earliest stages of development. The functional importance and the mechanisms by which cell size impacts embryo development are still largely understudied. The Xenopus early embryo provides a unique system to address these major gaps. Compared with other model organisms, the Xenopus early embryo is extremely large and contains a cell-size gradient, from small cells at the animal pole to large cells at the vegetal pole, across the entire embryo at stages around the mid-blastula transition. Here, we describe a protocol for dissociating single cells from Xenopus early embryos and sorting them by size using cell strainers with varying mesh pore sizes. As determined by imaging and size measurements, the sorted cells are within the expected size range and can be used for live-cell analysis or sequencing, or fixed for imaging. This system will shed new light on revealing size-dependent regulatory mechanisms during early development.