1 Introduction.- 2 Phylogenetic Development and Gross Anatomy of the Pineal Complex.- 3 Pineal Cell Biology and Innervation.- 3.1 General Aspects.- 3.2 Cell Biology of True Pineal Photoreceptors, Modified Pineal Photoreceptors, and Pinealocytes of the Mammalian Type.- 3.3 Central Innervation of the Pineal Organ.- 3.4 Sympathetic (Noradrenergic) Innervation of the Pineal.- 3.5 Parasympathetic Innervation of the Pineal Organ.- 3.6 Peptidergic Innervation of the Pineal Organ.- 4 Receptor Mechanisms and Second Messenger Systems Involved in the Regulation of the Melatonin Biosynthesis.- 4.1 General Aspects.- 4.2 Anamniotes.- 4.3 Birds.- 4.4 Mammals.- 5 Pineal Transcription Factors and Their Possible Roles for the Regulation of the Melatonin Biosynthesis.- 6 Action, Targets, and Receptors of Melatonin.- 7 Summary.- References.
