Animals Article Biological Clocks Biological oscillators Biological physics Biological traveling waves Cell Cycle Cell Nucleus Cell cycle dynamics Cytoplasm DNA Diffusion Female Giant Cells Models, Theoretical Nuclear Envelope Pacemaker dynamics Partial differential equations Xenopus cell-free extracts Xenopus laevis Xenopus laevis early development animal animal cell biological model biological rhythm cell cycle cell cycle protein cell free extract cell nucleus cell nucleus membrane