Pineal gland, perennial puzzle

Since antiquity this tiny intracranial appendicular organ has aroused sexual connotations and denials. Controversial and enigmatic, it played a significant part in the development of endocrinology and even neurosurgery. What was its histology, what was its role as a gland so intimately attached to the brain? What did comparative anatomists make of it in the light of its function as a 'third eye?' Mysticism and the famous Cartesian apothegm placed it in the center of Eastern and Western approaches to the mind-body problem and to mental disorders. The latter were connected with the common calcifications, so helpful in the radiological diagnosis of brain shifts due to mass lesions. Undefeated, even spurred by continuing uncertainties, researchers keep looking into this 'photo-neuro-endocrine transducer.'