Photodynamic activity of protoporphyrin IX in Harderian glands of Wistar rats: Monitoring by gland fluorescence

► The profile of fluorescence spectrum of Wistar rat Harderian glands varies under light irradiation. ► The variation level is in correlation with the gland tissue photodegradation level. ► The protoporphyrin IX is responsible for the gland fluorescence. ► The gland tissue photodegradation is realized via Type II photodynamic mechanism.