Saitama Medical University 1 article published in JoVE Developmental Biology Establishment of Proliferative Tetraploid Cells from Nontransformed Human Fibroblasts Susumu Ohshima1, Atsushi Seyama2 1Division of Morphological Science, Biomedical Research Center, Saitama Medical University, 2Department of Pathology, International Medical Center, Saitama Medical University Although proliferative polyploid cells are necessary to analyze chromosomal instability of polyploid cells, creating such cells from nontransformed human cells is not easy. The present report describes relatively simple procedures to establish proliferative tetraploid cells free of a diploid population from normal human fibroblasts.