Xenopus laevis Egg Extract
Cytoplasmic preparation of the egg of the African clawed frog, Xenopus laevis, that is capable of recapitulating many of the biochemical and physiological phenomena of the early embryonic cell cycle. These phenomena include nuclear envelope formation, DNA replication, DNA condensation, and mitotic spindle formation, all of which can occur after the addition of purified Xenopus sperm chromatin. Pioneered in the late 1980s/early 1990s by Andrew Murray, several different types of egg extracts can be produced that are either arrested in specific cell cycle stages, or undergo embryonic cycles as cyclin-dependent kinase 1 (CDK1) activity oscillates (Murray 1991).
Incubating unfertilized Xenopus eggs with EGTA prior to crushing them by centrifugation yields cytostatic factor (CSF) extract. Its name is derived from the basis that mature oocytes/eggs are...