Meiotic maturation

During female gamete production oocytes arrest during the diplotene stage of meiosis I before completing diakinesis and moving into meiosis II. In response to hormones, oocytes resume and complete meiosis to produce the final mature gametes. In C. elegans, meiotic maturation is triggered by major sperm protein through G-alpha-S-adenylate cyclase - protein kinase A (PKA) signaling and soma-to-germline communication.

Oogenesis

Oogenesis is the process of generating functional oocytes from an undifferentiated germ cell. In most animal species, oocytes arrest during meiotic prophase. The completion of meiosis and the preparation of the oocyte for fertilization are triggered in response to intercellular signaling in a process called meiotic maturation. During meiotic maturation, the oocyte transitions to metaphase of meiosis I, the nuclear envelope breaks down, the cortical cytoskeleton undergoes rearrangement, and the meiotic spindle is assembled. By contrast, in C. elegans, the processes of meiotic maturation, ovulation, and fertilization are temporally coupled. Meiotic maturation is triggered by major sperm protein (MSP), which acts as a hormone. In turn the maturing oocyte signals its own ovulation. During ovulation the oocyte passes through the spermatheca becoming fertilized on the way to the uterus.

Mitosis

Mitosis is part of the eukaryotic cell cycle and results in the production of two daughter cells each with a copy of the genome. The cell cycle itself is comprised of an interphase (made up of three stages G1, S, and G2) and the M (mitotic) phase. Cell growth, active transcription and translation, and DNA replication occur during interphase. During M phase duplicated DNA (chromatin) condense into sister chromatids (prophase); the nuclear envelop breaks down, kinetochore microtubles attach to the chromosomes and centrosomes are pushed to the poles of the growing spindle (prometaphase); the chromosomes are lined up on the metaphase plate (metaphase); sister chromatids are pulled to spindle poles at opposite ends of the cell (anaphase); the nuclear envelop is reformed and the chromatids decondense to chromatin (telophase); and the cell is cleaved into two by a contractile ring and the resolution of a cleavage furrow (cytokinesis). In some variant cell cycles nuclear division may not be followed by cell division, or G1 and G2 phases may be absent.