The invention provides for detecting target subpopulations of cells that have high proliferative and renewal properties in animals, including circulating tumor cells, cancer stem cells, hematopoietic stem cells and endothelial progenitor cells. The invention utilizes a defined substrate and media of known property to enrich target cell subpopulations which can be used for future genetic, proteomic and morphological analyses. The method can use image-capture and analysis software to characterize cells based on physical properties, such as size, morphology and kinetic properties.