Cytochalasin B, the name of which comes from the Greek cytos (cell) and chalasis (relaxation), is a cell-permeable mycotoxin. It was found that substoichimetric concentrations of cytochalasin B (CB) strongly inhibit network formation by actin filaments. Due to this, it is often used in cytological research. It inhibits cytoplasmic division by blocking the formation of contractile microfilaments. It inhibits cell movement and induces nuclear extrusion. Cytochalasin B shortens actin filaments by blocking monomer addition at the fast-growing end of polymers. Cytochalasin B inhibits glucose transport and platelet aggregation. It blocks adenosine-induced apoptotic body formation without affecting activation of endogenous ADP-ribosylation in leukemia HL-60 cells. It is also used in cloning through nuclear transfer. Here enucleated recipient cells are treated with cytochalasin B. Cytochalasin B makes the cytoplasm of the oocytes more fluid and makes it possible to aspirate the nuclear genome of the oocyte within a small vesicle of plasma membrane into a micro-needle. Thereby, the oocyte genome is removed from the oocyte, while preventing rupture of the plasma membrane. This alkaloid is isolated from a fungus, Helminthosporium dematioideum. History 1960s Cytochalasin B was first described in 1967, when it had been isolated from moulds by Dr W.B. Turner. Smith et al. found that CB causes multinucleation in cells and significantly affects cell motility. The multinucleated cells probably arise from failure of mitotic control, leading to variations in size and shape of interphase nuclei. 1970s In the 1970s, research on the mitosis of polynucleated cells was done. It appeared that these cells were created through progressive nuclear addition instead of nuclear division. The process by which this occurs is called pseudomitosis, which is the synchronous mitosis resulting in the division of just one nucleus. The separate nuclei are bound by a nuclear bridge and in binucleated cells the centrioles are doubled. Furthermore, it was found that CB causes the disorganization of the 50Å microfilaments of mouse epithelial cells which causes the cells to lose their shape. It also affects the appearance of young glands in cells and new gland formation in other cells. Another group found that CB inhibits the ability of HeLa cells to undergo cytokinesis by decomposition of the contractile ring. Research from 1971 showed that CB interferes with the release of iodine derived from thyroglobulin and blocks colloid endocytosis. Moreover, it was found that CB has an inhibitory effect on the uptake of sucrose-3H by chang-strain human