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.

Cell migration

Cell movement is an essential cell behavior for metazoan development. When this process is improperly orchestrated it can result in developmental disorders or pathologies such as tumor metastasis. In C. elegans, many cell types including canal associated neurons (CANs), hermaphrodite-specific neurons (HSNs), and Q neuroblasts migrate long distances during embryonic or larval development. Studies in C. elegans have elucidated many of the molecules required for stimulating and guiding the cell. These studies have shown that some directed movement rely on graded chemotactic signaling that is perceived by the cell and transduced to the cell's cytoskeleton. Chemotactic signaling molecules such as UNC-6, an extracellular matrix protein, can act as both an attractant, for cells expressing UNC-5, or as a repellant, for cells expressing UNC-40. Cell migration ultimately requires the regulation of cytoskeletal rearrangements. Studies have demonstrated UNC-73/Trio to be a main activator of Rac signaling in at least some of these migrating cells, which is proposed to drive such intracellular changes.