MPO and deep vein thrombosis: More recently, Nosaka has studied, through the use of immunohistochemical techniques, a model of stasis-induced DVT in mouse models: specifically, a 2009 study [33] compared the level of neutrophils (MPO+) and macrophages in clots of different ages, to establish a link between the time elapsed since the formation of thrombus and an inversion of the ratio between neutrophils and macrophages (N/M ratio) (Table 4).