Pyknotic Nuclei (IMAGE) Neural Regeneration Research Caption Pyknotic nuclei and prominent perineuronal spaces in the hippocampus of rats are visible in the group given the 50 mg/kg zinc supplement (hematoxylin-eosin staining, Leica, × 400). Credit <i>Neural Regeneration Research</i> Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.