This book is based on the NATO Advanced Research Workshop on "Mesenchymal-Epithelial Interactions in Neural Development" which was held in Berlin during March 1986. The idea that it may be the time for this workshop arose from a discussion among the organizers who met at a conference in Innsbruck. During the twenties, Spemann demonstrated that, in vertebrates, the formation of neuroepithelium depends on the induction by specific mesodermal derivatives. This was about the first time that mesenchymal-epithelial interactions had been recognized as an important mechanism in the development of an epithelial organ. Since then two things had become clear: 1) The identity and role of molecules, elaborated at mesenchymal-neuroepithelial interfaces had been partially elucidated in spinal cord and peripheral nerve ontogeny but, until recently, had been ignored in studies on the development of the brain. 2) In many-non-neural epithelia, the surrounding mesenchyme regulates such fundamental developmental steps as, for example, cell proliferation, morphogenesis and cell differentia­ tion, and there is no reason to exclude similar influences and interactions from brain development. It seemed to us that the importance and implications of many of these findings had not been appreciated by many developmental neurobiologists and that an attempt should be made to initiate discussions and exchange of ideas among different groups of scientists involved in extracellular matrix (ECM) research. This turned out to be a formidable task because of the great diversity of disciplines contributing findings to this active field.

1. Molecular and Cell Biology of the Extracellular Matrix (ECM).- Components of the Extracellular Matrix (Collagens, Elastin, Glycoproteins and Proteoglycans).- Structure, Expression and Function of Mouse Laminin.- Distribution of ECM Components in Early Embryos.- Production and Formation of the Basal Lamina.- Cell Surface and Extracellular Matrix Glycoproteins and Proteoglycans in Nervous Tissue.- Hyaluronectin and Hyaluronic Acid During the Development Rat of Brain Corte.- 2. Mesenchymal-Epithelial Interaction in the Morphogenesis of Epithelial Organs.- Control of Epithelial Polarity and Induction in the Early Chick Embryo.- Cell Interactions During Kidney Development.- Cell-Matrix Interaction in the Differentiation of the Intestinal Epithelium.- Connective Tissue and Ductular Metaplasia of Hepatocytes.- Effects of an Inhibitor of Proteoglycan Biosynthesis on Neuron-Induced Schwann Cell Proliferation and Basal Lamina Formation by Schwann Cells.- Mechanisms of Morphogenetic Specification in Skull Development.- Influence of the Notochord on the Morphogenesis of the Neural Tube.- Is There a Specific Interaction Between Donor Embryonic Entoderm (Chick or Quail) and Host Embryonic Mesoderm (Chick)?.- Influences of Meningeal Cells on the Development of the Brain.- 3. Cell Proliferation, Growth and Differentiation.- Fibroblast Growth Factor: Molecular and Biological Properties.- Hormonal Regulation of Epithelial Morphogenesis, Growth and Cytodifferentiation in Fetal and Adult Urogenital Tracts: Roles of Mesenchymal-Epithelial Interactions.- Influence of Meningeal Cells on the Development of Neuronal Cells in Primary Culture.- Influence of Meningeal Cells on Cell Proliferation in the Cerebellum.- Role of Medium and Substratum on Proliferation of Astroglia in Vitro.- 4. Cell Movement.- Hyaluronate-Cell Interactions in Morphogenesis and Tumorigenesis.- Secondary Neuroepithelial Stem Cells of the Cerebellum and the Dentate Gyrus are Attached to the Basal Lamina During Their Migration and Proliferation.- Migration of Neurons in Vivo.- 5. Growth of Neuronal Processes.- Mesenchymal-Epithelial Interactions During Neural Segmentation in the Chick Embryo.- Chemotropic Influence of Specific Target Epithelium on the Growth of Embryonic Sensory Neurites.- Substrates Influencing the Survival and Development of Neural Cells in Vitro.- The Role of Growth Cone Adhesion in Neuronal Morphogenesis, as Demonstrated by Interactions with Fibronectin and Laminin.- The Role of Basal Lamina in Axon Regeneration.- Retinal Axons and the Basal Lamina.- 6. Intracerebral Vascularization.- The Development of Intracerebral Blood Vessels Interacts with Astrocyte Development and Neuron Positioning in the Rat Neocortex.- Postnatal Development of ?-GT Activity in Rat Brain Microvessels. A Semiquantitative Histochemical Approach.- Development and Differentiation of the Blood-Brain Barrier.