This book is dedicated to the memory of two colleagues and friends, Amico Big- nami and Hendrick Vander Los. They were both pioneers in their fields: Bignami on on- togenesis and function of neuroglia, and Van der Los on brain plasticity and neuronal circuitry. Their ideas are further pursued by the authors in this book. Some of the chapters are products of a conference dedicated to these two scientists entitled "Recent Advances in Neurobiology: Plasticity and Regeneration." The conference was organized by the Insti- tute of Developmental Neuroscience and Aging and sponsored by the Region della Valle d' Aosta. Also, several chapters are written by colleagues who knew well either Amico or Hendrick and were invited to contribute to this dedication. The book is divided in four sections. The first part covers neurons, neuroglia includ- ing microglia, their plasticity and phenotypic expression, and specific functions and inter- actions. It is now established that neuroglia are an intimate component of the neuronal environment and thought to regulate several neuronal functions. More recently microglia have become prominent as the immune cells in the CNS. This part contributes new infor- mation for these cellular interactions. The second part deals with neuronal and glial cell plasticity as it relates to regeneration and neurodegeneration, more or less an extension of Part I. In recent years the role of transplantation in regeneration has become promising.

It has been established that neuroglia are involved in early neu- ronal growth, differentiation, and migration; these issues are well discussed in the companion volume entitled Neuron-Glia Interrela- tions During Phylogeny: I. Phylogeny and Ontogeny of Glial Cells. The present volume, Neuron-Glia Interrelations During Phylogeny: II. Plas- ticity and Regeneration, focuses on two aspects: (1) neuron-glia inter- relations as they relate to the physiological and metabolic homeostasis of neurons; and (2) the role of neuroglia and neuronal plasticity in regeneration and aging. Neuron-Glia Interrelations During Phylogeny: II. Plasticity and Regeneration begins with the unique presentation, "Neuron-Glia In- teractions in the Human Fetal Brain," by Sogos et al. The interesting issue discussed in this chapter is the immunocompetence of the CNS, a field that is now rising. The chapter by Oland et al. , "Glial Cells Playa Key Role in the Construction of Insect Olfactory Glomeruli," discusses a unique role of glial cells as intermediates in afferent- axon induction of substructure with the CNS. The chapter by Vanhems, "Insect Glial Cells and Their Relationships with Neurons," compliments the information presented in the companion volume by Fredieu and Mahowald and, in this volume, the chapter by Tobert and Oland. The chapter by Tsacopoulos and Poitry, "Metabolite Exchanges and Signal Trafficking Between Glial Cells and Neurons in the Insect Retina," provides evidence of the nutritive functions of glial cells and the important role of alanine supplied by glial cells to photoreceptors, a clear neuron-glia interaction.

One of the most impressive advances in the field of neuroscience over the last decade has been the accumulation of data on plasticity and regeneration in the nervous system of mammals. The book represents the contribution of a qroup of neuroscientists to this rapidly expanding field, through a Conference organized by the Institute of Developmental Neuroscience and Aging (IDNA). The meeting was held in Torino, Italy during April 1990 in honor of a great pioneer in the field of Neuroembryology, Professor Guido Filogamo. His introduction of the concept of neuroplasticity has had a significant impact on the study of neurobiology. This volume is divided into six sections, each focusing on one of the subject areas covered during the meeting Molecular and Cellular Aspects of Central and Peripheral Nervous System Development; Hormones,* Growth Factors, Heurotransmi tters, Xenobiotics and Development; In Vivo and in Vitro models of Development; Development and Regulation of Glia; Regeneration; and Aging.

The thalidomide tragedy which occurred slightly more than a decade ago made public officials and the general public acutely aware of the teratogenic potential of drugs. Although specialists in pharmacology and developmental biology had been studying this problem many years before, this catastrophic episode triggered the passage of legislation which required that information about the teratogenicity of drugs be produced before the drugs could be available to the general public. Gross deformities in man produced by drugs are frequently difficult to reproduce in experimental animals and the changes which are produced in other animals are frequently not translatable to humans. The problem of evaluating the potential that drugs have to produce gross malformations is small, however, compared to the evaluation of subtle but permanent behavioral effects which drugs may exert upon the developing organism. Nevertheless, many experimental studies in recent years indicate that subtle biochemical changes produced by drugs on brain tissue during critical periods of fetal or early post natal maturation may become manifest subsequently as behavioral deviations in early childhood or adolescence. Hyperkinetic disorders, epilepsies and other developmental disabilities may have a subtle biochemical imbalance, perhaps drug induced, as an underlying factor. This symposium was organized with the intent of bringing to gether prominent investigators who are working in different aspects of brain development and who are interested in the effects of drugs on the developing brain in order to discuss their findings, pro pose new theories, and open new avenues for future research."

The last decade has generated a multitude of studies using in vitro model systems to explore growth and differentiation of the nervous system. Although the findings have been exciting and have revealed unique properties of neural cells, considerable concern continues to be expressed regarding the significance of in vitro findings in terms of their applicability to in vivo biological events. To examine this issue further, a group of scientists pre sented and discussed their findings at a conference sponsored by the Institute of Developmental Neuroscience and Aging held in Crete, Greece, 26-29 May 1985. The conference was cosponsored by the University of Crete and was generously supported by the Ministry of Research and Technology of Greece, Tourism Organization of Greece, and also Sandoz and FIDIA. The Directors of the Institute of Developmental Neuroscience and Aging are indebted to these Institutions for their support. For the success of this conference, the Directors owe much to Drs. Eleni Fleischer-Lambropoulos and Yiannis Tsouderos, who spent countless hours in making arrangements so that the participants would have not only a scientific, but also a unique cultural, experience. Several chapters of this book focus on the complex phenomena of neurogenesis and gliogenesis, and the modulation of neuronal differentiation. The concept that neuronal differentiation has both genetic and epigenetic components is documented by elegant studies using both in vitro cultured cells and neurons transplanted in vivo."

It is now established that neuroglia are the intimate partners of neurons and that neuronal function is a result of neuron-glia interrelations at several levels of organization. The literature shows that the study of phylogeny has contributed a deeper understand- ing of the complex functions of the neuroglia and the neuron-glia unit. It is the purpose of Neuron-Glia Interrelations During Phylog- eny: I. Phylogeny and Ontogeny of Glial Cells, as well as its compan- ion volume Neuron-Glia Interrelations During Phylogeny: II. Plasticity and Regeneration, to present to the scientific community a broad spectrum of information on neuroglia through phylog- eny and ontogeny, the focus of this volume. In view of the role of neuroglia in plasticity and regeneration, the companion volume will cover this aspect of neuroglia during phylogeny. Neuron-Glia Interrelations During Phylogeny: I. Phylogeny and Ontogeny of Glial Cells begins with the elegant chapter "Glial Types, Gliogenesis, and Extracellular Matrix in Mammalian CNS" by Amico Bignami, to whom this volume is dedicated. He was one of the pioneers in describing gliogenesis and this chapter brings together everything we know today on this critical topic. It also includes the latest views of Bignami on the role of extracellular matrix in gliogenesis and glial functions. "Evolution of Astrocytes in the Vertebrate CNS" by Suarez et al. complements and extends the information in Bignami's chapter by including ependymal astrocytes.

This book is dedicated to the memory of two colleagues and friends, Amico Big- nami and Hendrick Vander Los. They were both pioneers in their fields: Bignami on on- togenesis and function of neuroglia, and Van der Los on brain plasticity and neuronal circuitry. Their ideas are further pursued by the authors in this book. Some of the chapters are products of a conference dedicated to these two scientists entitled "Recent Advances in Neurobiology: Plasticity and Regeneration." The conference was organized by the Insti- tute of Developmental Neuroscience and Aging and sponsored by the Region della Valle d' Aosta. Also, several chapters are written by colleagues who knew well either Amico or Hendrick and were invited to contribute to this dedication. The book is divided in four sections. The first part covers neurons, neuroglia includ- ing microglia, their plasticity and phenotypic expression, and specific functions and inter- actions. It is now established that neuroglia are an intimate component of the neuronal environment and thought to regulate several neuronal functions. More recently microglia have become prominent as the immune cells in the CNS. This part contributes new infor- mation for these cellular interactions. The second part deals with neuronal and glial cell plasticity as it relates to regeneration and neurodegeneration, more or less an extension of Part I. In recent years the role of transplantation in regeneration has become promising.

It has been established that neuroglia are involved in early neu- ronal growth, differentiation, and migration; these issues are well discussed in the companion volume entitled Neuron-Glia Interrela- tions During Phylogeny: I. Phylogeny and Ontogeny of Glial Cells. The present volume, Neuron-Glia Interrelations During Phylogeny: II. Plas- ticity and Regeneration, focuses on two aspects: (1) neuron-glia inter- relations as they relate to the physiological and metabolic homeostasis of neurons; and (2) the role of neuroglia and neuronal plasticity in regeneration and aging. Neuron-Glia Interrelations During Phylogeny: II. Plasticity and Regeneration begins with the unique presentation, "Neuron-Glia In- teractions in the Human Fetal Brain," by Sogos et al. The interesting issue discussed in this chapter is the immunocompetence of the CNS, a field that is now rising. The chapter by Oland et al. , "Glial Cells Playa Key Role in the Construction of Insect Olfactory Glomeruli," discusses a unique role of glial cells as intermediates in afferent- axon induction of substructure with the CNS. The chapter by Vanhems, "Insect Glial Cells and Their Relationships with Neurons," compliments the information presented in the companion volume by Fredieu and Mahowald and, in this volume, the chapter by Tobert and Oland. The chapter by Tsacopoulos and Poitry, "Metabolite Exchanges and Signal Trafficking Between Glial Cells and Neurons in the Insect Retina," provides evidence of the nutritive functions of glial cells and the important role of alanine supplied by glial cells to photoreceptors, a clear neuron-glia interaction.

It is now established that neuroglia are the intimate partners of neurons and that neuronal function is a result of neuron-glia interrelations at several levels of organization. The literature shows that the study of phylogeny has contributed a deeper understand- ing of the complex functions of the neuroglia and the neuron-glia unit. It is the purpose of Neuron-Glia Interrelations During Phylog- eny: I. Phylogeny and Ontogeny of Glial Cells, as well as its compan- ion volume Neuron-Glia Interrelations During Phylogeny: II. Plasticity and Regeneration, to present to the scientific community a broad spectrum of information on neuroglia through phylog- eny and ontogeny, the focus of this volume. In view of the role of neuroglia in plasticity and regeneration, the companion volume will cover this aspect of neuroglia during phylogeny. Neuron-Glia Interrelations During Phylogeny: I. Phylogeny and Ontogeny of Glial Cells begins with the elegant chapter "Glial Types, Gliogenesis, and Extracellular Matrix in Mammalian CNS" by Amico Bignami, to whom this volume is dedicated. He was one of the pioneers in describing gliogenesis and this chapter brings together everything we know today on this critical topic. It also includes the latest views of Bignami on the role of extracellular matrix in gliogenesis and glial functions. "Evolution of Astrocytes in the Vertebrate CNS" by Suarez et al. complements and extends the information in Bignami's chapter by including ependymal astrocytes.

The last decade has generated a multitude of studies using in vitro model systems to explore growth and differentiation of the nervous system. Although the findings have been exciting and have revealed unique properties of neural cells, considerable concern continues to be expressed regarding the significance of in vitro findings in terms of their applicability to in vivo biological events. To examine this issue further, a group of scientists pre sented and discussed their findings at a conference sponsored by the Institute of Developmental Neuroscience and Aging held in Crete, Greece, 26-29 May 1985. The conference was cosponsored by the University of Crete and was generously supported by the Ministry of Research and Technology of Greece, Tourism Organization of Greece, and also Sandoz and FIDIA. The Directors of the Institute of Developmental Neuroscience and Aging are indebted to these Institutions for their support. For the success of this conference, the Directors owe much to Drs. Eleni Fleischer-Lambropoulos and Yiannis Tsouderos, who spent countless hours in making arrangements so that the participants would have not only a scientific, but also a unique cultural, experience. Several chapters of this book focus on the complex phenomena of neurogenesis and gliogenesis, and the modulation of neuronal differentiation. The concept that neuronal differentiation has both genetic and epigenetic components is documented by elegant studies using both in vitro cultured cells and neurons transplanted in vivo."