“…While "discrete" in-silico models (e.g., DiMilla et al, 1991, Dickinson & Tranquillo et al, 1993, Kansal et al, 2000a, 2000b, Patel et al, 2001, Ferreira et al, 2002, Turner & Sherratt, 2002, Leyrat et al, 2003, dos Reis et al, 2003, Anderson, 2005 are able to capture individual cell migration and easily incorporate biological rules, such as cell-cell & cell-medium interactions and motion due to chemotaxis and haptotaxis, they are limited to relatively small numbers of cells due to computational cost, among the other deficiencies and oversimplifications introduced by the discrete approach. In contrast, "continuum" models (e.g., Byrne & Chaplain, 1995a, 1995b, 1996a, 1996b, Bellomo & Preziosi, 2000, Cristini et al, 2003, Macklin & Lowengrub, 2005, Frieboes et al, 2006a, Li et al, 2007, Macklin & Lowengrub, 2007, describing tissue matter as a continuum medium rather that discrete individual cells, capture the collective motion of FCCMUs with less computational expense.…”