Spindle flow stability

Intracellular transport plays a key role in fundamental cellular processes such as cell division. Advection by cytoplasmic streaming, the persistent flow of fluid inside a cell, is an example of active transport in eukaryotic cells. Experimental studies on mouse oocytes (immature egg cells) have investigated the influence of intracellular flow in meiosis II (cell division resulting in reproductive cells). In meiosis II, the spindle (the protein structure responsible for dividing the genetic material in a cell) maintains its position near the cortex (thin actin network bound to the cell membrane) for hours to days. The stable positioning of the spindle in the oocyte beneath the cortical cap, which is rich in filamentous actin and myosin-II motor proteins, is accompanied by cytoplasmic streaming, driven by the flow of actin filaments away from the cortical cap. In this talk, we use a combination of numerical and analytical modelling to reveal the physical origin of the stability of the spindle.