Staining (IMAGE) Neural Regeneration Research Caption Nissl staining showed that exogenous progesterone (8 mg/kg) increased the number of intact pyramidal cells in the hippocampal CA1. 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.