[15] Maintenance of Xenopus laevis and oocyte injection

This chapter explains the maintenance of Xenopus laevis and oocyte injection. There are six species of Xenopus, all indigenous to Africa, but Xenopus laevis is the only one commonly used in laboratory research. To synchronize oocyte development, the frogs can be injected with human chorionic gonadotropin (hCG), which induces ovulation and egg laying, after which oocyte development starts over approximately synchronously. Xenopus can tolerate a wide range of temperature fluctuations, but the quality of oocytes diminishes markedly following temperature shifts. Therefore, frogs should be housed in a temperature-controlled environment. Xenopus are very susceptible to desiccation, and they can die from being out of the water for a few hours. Oocytes from Xenopus laevis can be classified into six stages of development on the basis of anatomy; the choice of which stage oocytes to inject depends on the purposes of the experiment.