Subpopulations of tumor cells make up a neoplastic lesion that is primarily characterized by a blood supply that clonally and subclonally determines evolution of proliferation and infiltration of the cells. Proximity to blood vessels and subsequent proliferation of the neoplastic cells that infiltrate stroma or neuropil would undergo progressive increase in tumor grade and develop tumor necrosis and abnormal mitotic figures. Such clonally evolving subpopulations of neoplastic cells would give rise to differentiation and dedifferentiation mechanisms in the evolution of various cell subsets that determine blood supply dynamics of influence in their own right. Neoplasms constitute disturbances in blood supply that clonally progress as attributes of a cell of origin. Such a cell would variably differentiate, proliferate and spread according to an otherwise artificial concept of tumor grade and of stage of the lesion. Blood vessels would participate in the clonal proliferation of tumor cells beyond simple considerations of differentiation or dedifferentiation of the lesion but in terms of subpopulations of the neoplastic cells proximal or less proximal to the vessels.