ABSTRACT
The modern history of the pineal gland probably began with the discovery, in 1917,[1] that extracts of cow pineals could lighten the skin of frogs. The physiological significance of this relationship seemed obscure, inasmuch as bovine pineal extracts had no effect on pigmentation in bovines (or humans), and frog pineals lacked detectable skin-lightening ability. However, the finding did indicate that the pineal contained a compound with at least some biological activity, and it provided a way of identifying the active compound, using assays based on the ability of purified extracts to aggregate the melanin granules in the frog’s pigment cells. In 1958, Lerner et al.[2] discovered the compound’s chemical structure to be 5-methoxy-N-acetyltryptamine and named it melatonin.
