Obtaining Xenopus tropicalis Embryos by Natural Mating

Abstract

Xenopus is a powerful model system for cell and developmental biology in part because frogs produce thousands of eggs and embryos year-round. Natural matings are a simple and common method to obtain embryos for injection or other experimental use or to raise to adulthood. This method does not require sacrificing a male as in vitro fertilization (IVF) does. Male and female frogs are injected with an ovulation hormone, placed together in a mating bucket, and left for 4–6 h or overnight to mate. Embryos are then collected, treated with cysteine to remove the sticky jelly coat, and used for injections and/or raised to later stages or adulthood. For embryos raised past free-swimming stages, the cysteine step can optionally be skipped, and tadpoles can be allowed to hatch naturally from the jelly coat. Although there are many similarities between natural mating protocols for Xenopus laevis and Xenopus tropicalis, there are key differences such as hormone dosage, timing of ovulation, and embryo incubation temperature. Here we provide a specific protocol for inducing natural matings in X. tropicalis.