Harderian Gland: An Extraretinal Photoreceptor Influencing the Pineal Gland in Neonatal Rats?

Abstract

The circadian rhythm of pineal serotonin and the influence of light on that rhythm have been confirmed. Removal of the Harderian gland abolishes the response to light in blinded animals, which suggests that this gland may act as the extraretinal transducer involved in the persistence of the pineal rhythm in blinded suckling rats.