Xenopus laevis Egg Extracts.

Xenopus laevis egg extracts represent one of the most versatile tools for biochemical analyses of complex cellular processes in a controlled in vitro environment. Developed from unfertilized oocytes, these extracts preserve the biochemical richness of the early embryonic cytoplasm, which is preloaded with maternal factors to drive rapid cell cycles without transcription. Historically, pioneering work by Lohka and Masui established the first cell-free system capable of nuclear assembly and chromosome condensation, while subsequent studies by Blow, Laskey, Newport, Kirschner, and others demonstrated faithful DNA replication. Over time, distinct extract types have emerged, including low-speed supernatant, high-speed supernatant, and nucleoplasmic extract, each tailored to specific mechanistic questions, from nuclear envelope formation to replisome dynamics. These systems have enabled to characterize fundamental principles of cell-cycle control, chromatin organization, and genome stability, and continue to underpin research in DNA replication, nuclear transport, spindle assembly, and checkpoint regulation.