abnormal Harderian gland physiology abnormal Harderian gland porphyrin secretion anomaly in the production and/or release of porphyrin(s), the pigment(s) responsible for the red discoloration of ocular and/or nasal discharges in rodents; in rats, protoporhyrin IX accounts for most of the porphyrin produced and stored in the Harderian gland; in some rodents the concentration of porphyrins in the Harderian glands varies according to sex and species, and tends to be higher in females than in males MP:0013476