Zebrafish (IMAGE) Penn State Caption Melanin is visualized in a silver-stained, 5-day-old zebrafish using X-ray histotomography. The different colors were assigned based on the depth of the melanin in cells within the sample from top to bottom. Credit Keith Cheng Lab, Penn State College of Medicine Usage Restrictions None License Original 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.