 Using injections of thymidine-H3 to label the nuclei of dividing cells, Altman was able to use autoradiography to determine a neuronal birthdate for each cell in a rat's brain.This research revealed some degree of adult neurogenesis in the hippocampus and olfactory bulb of rats, and paved the way for the possibility of neuropoiesis in the adult mammalian brain.Following Altman's work, thymidine-H3 injections were used to examine the brains of a variety of other species.