In the first section of this volume, we have attempted to bring together some of the papers that reflect exciting new areas of development in relation to neuroendocrine investigation. Very recently, specific nucleotide recognition sequences for thyroid hormones, steroid hormones and the fundamental intracellular regulator, cyclic AMP, have been determined. In this section, the preliminary characterization and investigation of the nuclear binding proteins that mediate the actions of cAMP are described. Not only does this represent an important advance in cell biology, but it may represent a further level of alteration in control in normal and disease states. Intercellular pituitary "cross talk" is well described in the in vitro setting. The active molecules are clearly It is now important able to exert significant actions at the subnanomolar level. to design experiments in order to define the precise physiological relevance of these novel and potentially important observations. Paracrine and autocrine cellular interactions are of established importance in growth control in a variety of body tissues. But it is only very recently that the investigation of normal and abnormal anterior pituitary growth has reached the forefront of neuroendocrine research. This is perhaps surprising, beause the inhibitory effects of doapmine agonism on lactotroph growth and differentiation have been appreciated for some time. The anterior pituitary gland produces numerous growth factors that exert a variety of functional effects on pituitary hormone synthesis and release.