Pigmentation Process (IMAGE) Manning Selvage & Lee Caption A series of events occur within pigment cells to trigger the production of melanin. The process can be activated by both external influences, such as UV radiation or irritants, or internal influences such as hormones. Once melanin is formed it is Credit Manning, Selvage & Lee 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.