Which rodent type contains more porphyrin in the secretions from the Harderian gland?

• A. PEW's (Pink Eyed White Rats)
• B. Albino rats
• C. Guinea pigs
• D. Mice

Answer: (A)

Porphyrin is a pigment produced during heme breakdown that can be secreted by the Harderian gland along with tears. In rodents, the amount of this porphyrin in Harderian secretions varies by strain. The Pink-Eyed White rat has a genetic background that drives especially high porphyrin production in this gland, producing noticeable reddish or orange tear staining around the eyes. That makes their Harderian secretions contain more porphyrin compared with the other listed rodents. Albino rats, mice, and guinea pigs can have porphyrin in their secretions as well, but not to the same extent as the Pink-Eyed White rats, so the best answer is the Pink-Eyed White rat.