The Beginnings of the Pineal Scientific Era: From the Late Nineteenth Century to Melatonin’s Discovery

Abstract

In the late nineteenth century, and based on histological studies, the mammalian pineal gland was classified as a rudimentary vestigial organ, a remnant of the third eye of the lacertids or cold-blooded vertebrates. In the early twentieth century, there was speculation that the pineal gland was a predominantly glial organ. In 1930, Pío del Río-Hortega, one of the most outstanding figures of the Spanish Histological School, employed silver staining to study the human pineal gland. Río-Hortega identified secretory pineal cells and interstitial cells of a neuroglial origin. In 1954, Aaron B. Lerner began working on the isolation of a pineal skin lightening factor in amphibians, which led 4 years later to the identification of melatonin, a finding that had an explosive impact on pineal research.