Keywords: comparative neuroendocrinology and neuroscience, comparative reproductive endocrinology, comparative molecular endocrinology, evolution of neurohormones and receptors, evolution of glycoprotein hormones and receptors, 5' Flanking Region, Adaptation, Physiological, Adrenal Glands, Adrenocorticotropic Hormone, Aggression, Alkaline Phosphatase, alpha-MSH, Amino Acid Motifs, Amino Acids, Androgens, Antigen-Antibody Reactions, Anura, Ascorbic Acid, Atlantic Ocean, Atrazine, Autoradiography, Axons, beta-Endorphin, beta-MSH, Bicuculline, Binding Sites, Binding, Competitive, Biological Assay, Blood Glucose, Blood Proteins, Blotting, Northern, Blotting, Western, Body Size, Brain Chemistry, Bufo marinus, Carrier Proteins, Cecum, Cell Count, Cell Division, Cell Line, Tumor, Cell Membrane, Cell Nucleus, Central Nervous System, Cercopithecus aethiops, Cerebellum, Cerebral Ventricles, Chickens, Chordata, Nonvertebrate, Chromatography, Chromatography, Affinity, Chromatography, Gel, Chromatography, High Pressure Liquid, Cloning, Molecular, Consensus Sequence, Corpus Luteum, Corticotrophs, COS Cells, Cross Reactions, Culture Media, Conditioned, Culture Techniques, Cyclic AMP, Cyclization, Cypriniformes, Cyprinodontiformes, Cytosol, Decapoda (Crustacea), Dextrans, Diencephalon, Diffusion, Dizocilpine Maleate, DNA Primers, DNA, Complementary, Dogfish, Echinodermata, Elasmobranchii, Electrophoresis, Polyacrylamide Gel, Embryonic Development, Environmental Monitoring, Environmental Pollutants, Estradiol, Excitatory Amino Acid Antagonists, Exons, Fatty Acids, Fatty Acids, Nonesterified, Fetal Proteins, Fish Proteins, Fishes, Fluorescent Antibody Technique, Follicle Stimulating Hormone, Forelimb, Fresh Water, Frozen Sections, Gametogenesis, gamma-Aminobutyric Acid, Gene Components, Gene Expression, Gene Expression Profiling, Gene Expression Regulation, Genes, Genetic Variation, Genome, Genomics, Geologic Sediments, Glucose, Glutamate Decarboxylase, Glycoconjugates, Glycoproteins, Gonadal Steroid Hormones, Gonadotrophs, Gonadotropin-Releasing Hormone, Gonadotropins, Gonadotropins, Pituitary, Gonads, Granulocyte-Macrophage Colony-Stimulating Factor, Growth Hormone, Guinea Pigs, Hagfishes, Haplorhini, Hazardous Substances, Herbicides, Hindlimb, Histocytochemistry, Hormones, Horseradish Peroxidase, Hydroxyprogesterones, Hydroxytestosterones, Hypophysectomy, Hypothalamic Hormones, Hypothalamo-Hypophyseal System, Hypothalamus, Hypothalamus, Anterior, Hypothalamus, Posterior, Immune Sera, In Situ Hybridization, Injections, Intraperitoneal, Injections, Intraventricular, Inositol Phosphates, Insulin, Interleukin-1, Introns, Invertebrates, Lampreys, Larva, Lectins, Leptin, Life Cycle Stages, Limb Deformities, Congenital, Luciferases, Luteinizing Hormone, Mammals, Mass Spectrometry, Melanins, Melanocyte-Stimulating Hormones, Melanotrophs, Mesencephalon, Metamorphosis, Biological, Microscopy, Electron, Microscopy, Polarization, Molecular Probes, Muscimol, Mutagenesis, Site-Directed, Narcotic Antagonists, Nerve Fibers, Nerve Tissue Proteins, Neuropeptide Y, Neuropeptides, Neurosecretory Systems, Neutralization Tests, New Hampshire, Nitric Oxide, Oceans and Seas, Olfactory Pathways, Oligopeptides, Oncorhynchus mykiss, Oocytes, Organ Specificity, Ovarian Follicle, Ovariectomy, Ovary, Ovulation, Ovulation Induction, Penaeidae, Peptide Fragments, Peptide Mapping, Peptides, Perfusion, Petromyzon, Pheromones, Pituitary Gland, Pituitary Gland, Anterior, Pituitary Gland, Posterior, Pituitary Hormone-Releasing Hormones, Pituitary Hormones, Pituitary Hormones, Anterior, Pituitary Neoplasms, Preoptic Area, Pro-Opiomelanocortin, Progesterone, Prolactin, Prolactin-Releasing Hormone, Promoter Regions, Genetic, Prosencephalon, Protein Binding, Protein Isoforms, Protein Precursors, Protein Processing, Post-Translational, Protein Structure, Secondary, Proteins, Pyrrolidonecarboxylic Acid, Radioimmunoassay, Rana catesbeiana, Rana pipiens, Rana ridibunda, Ranidae, Receptors, Cell Surface, Receptors, Estrogen, Receptors, Leptin, Receptors, LHRH, Receptors, N-Methyl-D-Aspartate, Receptors, Peptide, Receptors, Pituitary Hormone, Receptors, Thyrotropin, Recombinant Fusion Proteins, Recombinant Proteins, Reproduction, Reverse Transcriptase Polymerase Chain Reaction, Rhombencephalon, RNA, RNA Precursors, Salmon, Seawater, Secretory Rate, Sequence Alignment, Sequence Analysis, Sequence Analysis, DNA, Sequence Analysis, Protein, Sexual Behavior, Animal, Sexual Maturation, Skates (Fish), Skin, Sodium, Sodium Chloride, Somatomedins, Somatostatin, Somatotrophs, Songbirds, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Sperm Transport, Spermatogonia, Spermatozoa, Statistics as Topic, Synteny, Tachykinins, Telencephalon, Teratogens, Testis, Testosterone, Thyroid Gland, Thyroid Hormones, Thyrotropin-Releasing Hormone, Thyroxine, Tissue Distribution, Triglycerides, Triiodothyronine, Trout, Urochordata, Urotensins, Uterus, Vasotocin, Vertebrates, Vocalization, Animal, Water Pollutants, Water Pollutants, Chemical, Weight Gain, Xenopus, evolution, receptor, Evaluation Studies as Topic, Biological Evolution, hormone, Lamprey, G protein-coupled receptors, Pituitary, basal vertebrate, structure-activity relationship, Sequence Homology, Amino Acid, Seasons, Sex Characteristics, Likelihood Functions, Species Specificity, Statistics, Nonparametric, Evolution, Molecular, Models, Genetic, Sex Factors, Sequence Homology, Osmolar Concentration, Sequence Homology, Nucleic Acid, Food Chain, Models, Anatomic, gonadotropin-releasing hormone receptors, lamprey hypothalamus, lamprey reproduction, LPXRF-amide peptide family, neuroendocrine control in lamprey, Rfamide peptides, agnathan, Gonadotropin, neuroendocrine, estrogen receptor, GnIH, GnRH