Humoral Interrelations of the Pineal Gland with Lateral Eyes and Orbital Glands

Abstract

Three kinds of general interrelationships are currently accepted concerning the pineal gland, the lateral eyes and the glands of the orbit: (1) The mammalian pineal gland has evolved from eye-like structures (“median or third eyes”) in the pineal complex of lower vertebrates, and its specialized parenchymal cells, the pinealocytes, have residual features of photoreceptor cells (Collin, 1969, 1979; and reviews by Oksche and Kappers in the present volume). (2) The mammalian pineal gland, starting a few days after birth, receives its photic input via the lateral eyes, CNS and sympathetic innervation (Wurtman et al., 1967; Moore et al., 1968; Klein and Moore, 1979). (3) Pineal gland, lateral eye retina, and, to a lesser degree, the Harderian gland of the orbit, share some special biochemical characteristics or capacities. At the present time, the best known and most relevant of these shared characteristics is the presence of the melatonin-forming enzyme, hydroxyindole-O-methyltransferase (HIOMT)(Quay, 1965; Quay et al., 1969; Cardinali and Wurtman, 1972; Nagle et al., 1972a, 1972b, 1974; Cardinali et al., 1974; Pevet et al., 1978; Suzuki and Yagi, 1978; Balemans et al., 1980; Pevet et al., 1980a, 1980b, 1981; Ralph, 1980; Vivien-Roels et al., 1981) and its 5-methoxyindole products (Bubenik et al., 1974, 1976a, 1976b; Pang et al., 1977, 1980; Reiter et al., 1981; Yu et al., 1981).