Cell cortex

Due to the branching process and the density of the actin cortex, the cortical cytoskeleton can comprise a highly complex meshwork such as a fractal structure.

[12] In mitosis, F-actin and myosin II form a highly contractile and uniform cortex to drive mitotic cell rounding.

The surface tension produced by the actomyosin cortex activity generates intracellular hydrostatic pressure capable of displacing surrounding objects to facilitate rounding.

[16][17] Genetic studies have shown that the cell cortex in mitosis is regulated by diverse genes such as Rhoa,[18] WDR1,[19] ERM proteins,[20] Ect2,[21] Pbl, Cdc42, aPKC, Par6,[22] DJ-1 and FAM134A.

By pulling on adhesion complexes, the cortex promotes the expansion of contacts with other cells or with the extracellular matrix.

Notably, during early mammalian development, the cortex pulls cells together to drive compaction and the formation of the morula.

[26][27] Also, differences in cortical tension drives the sorting of the inner cell mass and trophectoderm progenitors during the formation of the morula,[28] the sorting of germ layer progenitors during zebrafish gastrulation,[29][30] the invagination of the mesoderm and the elongation of the germ band elongation during drosophila gastrulation.

F-actin distribution in the cell cortex as shown by rhodamine phalloidin staining of HeLa cells that constitutively express Histone H2B - GFP to mark chromosomes . F-actin is thus red, while Histone H2B is displayed in green. The left-hand cell is in mitosis , as demonstrated by chromosome condensation, while the right-hand cell is in interphase (as determined by intact cell nucleus ) in a suspended state. In both cases, F-actin is enriched around the cell periphery. Scale bar: 10 micrometers.