Anaplasia (from ancient Greek: ἀνά ana, "backward" + πλάσις plasis, "formation") is a condition of cells in which they have poor cellular differentiation, losing the morphological characteristics of mature cells and their orientation with respect to each other and to endothelial cells. The term also refers to a group of morphological changes in a cell (nuclear pleomorphism, altered nuclear-cytoplasmic ratio, presence of nucleoli, high proliferation index) that point to a possible malignant transformation.