Thus, the most fundamental cell cycle definition is that between M phase and Interphase. The salient features of mitosis are Nuclear envelope breakdown, Chromosomal condensation, Assembly of the mitotic spindle, Alignment of duplicated sister chromosomes along the metaphase plate, and Chromosomal segregation, the metaphase to anaphase transition . The most conspicuous feature of Interphase is chromosomal DNA replication, also known as S phase. Embryonic cell cycles alternate between rapid S phase and M phase without growth and can complete cell division cycles in a few minutes. In addition to making and segregating sister chromosomes, embryonic cells are also subdividing and organizing the fertilized oocyte into a multicellular body plan.
Embryonic cells are a good example of how there can be cell division without growth.
Differentiated cell-division cycles almost always involve growth. Such cells use environmental signals to coordinate growth with division. Differentiated cells are not fully occupied with S phase and M phase and spend most of their time prior to commitment to S phase, in G1, or prior to commitment to M phase, in G2. In G1, a liver cell can be a liver cell and brain cell be a brain cell. In G2, unfertilized oocytes remain in stand-by mode for decades.