Abstract Zinc ion-induced changes in nerve tissue were analyzed by electron microscopy. Four-week-old cultures of dorsal root ganglia explanted from 13- to 14-day-old mouse embryos were incubated in media containing several concentrations of added zinc ions. After 24 h in 1 mm zinc sulfate, most axons appeared swollen and contained few neurotubules. Instead, sheets and long structures with a diameter of approximately 250 nm were found. These abnormal structures morphologically resembled the zinc ion-induced aggregates of tubulin that formin vitro. Many neurons showed extensive vacuolation and degenerative changes, while most other cells appeared unchanged. Lower concentrations of zinc ions and/or shorter incubation times resulted in smaller changes in the number and structure of the neurotubules, fewer abnormal structures, less swelling of axons, and more conspicuous changes in the nuclei of neurons. This study demonstrates that neurotubule assembly and/or disassembly in dorsal root ganglion cultures is susceptible to the concentration of zinc ions and suggests that the divalent cationic environment can influence the structure and function of cells containing neurotubules.