Prolactin Releasing and Inhibiting Factors in the Posterior Pituitaiy.- The Hypothalamo-Pituitary Axis.- Structure-Function Relationship.- Vascular Connections.- Innervation.- Posterior Pituitary Dopamine.- Inhibition of PRL Secretion.- Changes in Synthesis and Turnover Rates.- Regulation of Release.- Posterior Pituitary PRF.- Participation in PRL Release under Different Physiological Conditions.- PRF Activity In Vitro and In Vivo.- Biochemical and Physiological Characterization of PRF.- Cellular Origin.- Summary.- Effects of Prolactin on Target Cells.- Target and Actions of Prolactin.- Reproduction.- Mammary Gland.- Ovary.- Testis.- Accessory Sex Glands.- Feto-Placental Unit.- Homeostatic Mechanisms.- Electrolyte Balance.- Adrenal Gland.- Immune Function.- Liver.- Vasculature.- Feedback Effects.- Additional Actions.- The Signal Transduction Pathway of Prolactins Actions.- Prolactin and the Prolactin Receptor.- The Prolactin Molecule.- The Prolactin Receptor.- Prolactin-Receptor Complex.- Putative Second Messengers.- Cyclic Nucleotides.- Ions and Ion Channels.- Polyamines.- Prostaglandins and Leukotrienes.- The Phosphatidylinositol-Protein Kinase C System.- Alternative Future Approaches.- Indirect Effects of Prolactin on Target Tissues.- Synlactin.- Evidence for the Existence of Synlactin.- Physiologic Relevance of Synlactin.- Biochemical Characteristics of Synlactin.- Liver Lactogenic Factor.- Evidence for the Existence of Liver Lactogenic Factor.- Physiologic Relevance of LLF.- Biochemical Characteristics of LLF.- Speculation about Synlactin and LLF.- Conclusion.- Cellular and Molecular Aspects of the Neuroendocrine-Immune Dialogue in T-Cell Differentiation.- Cell Populations of the Thymic Microenvironment.- Pathways of T-Cell Differentiation.- Neural Crest Contribution to Thymic Development.- Neuroendocrine Markers of the Thymus.- Intrathymic Synthesis of Neuropeptides.- Thymic Neuropeptide Receptors.- Physiological Significance of Intrathymic Neuropeptide Synthlă.