Although it is the defining organ of the Chordata, the notochord and its cells are one of the least understood vertebrate organs. This may be because large parts of the notochord are often replaced with cartilaginous or bony vertebral bodies. The presence of cartilage in the notochord raises questions about the evolutionary relationships between notochord cells and cartilage cells. This book integrates classical analytical studies with recent palaeontological, experimental, and molecular studies in both developmental and evolutionary contexts. For example, although the early signaling function of the notochord is conserved across the vertebrates, many will be surprised to find that the role of the notochord in vertebral body development in tetrapods is not the blueprint for all vertebrates. Recent studies on zebrafish and medaka embryos have uncovered the molecular mechanisms of a somite-independent notochord-driven segmentation process that establishes vertebral centra and intervertebral spaces. As this process is not restricted to teleosts, the authors have written a general discussion about the role of the notochord in vertebral formation. Modularity and segmentation of the vertebral column are related topics. Further overarching themes are the structure, function and fate of the notochord in adult vertebrates and notochord–cartilage relationships. Key Features The first book devoted to notochord development, function and evolution Includes and integrates information on the notochord from studies going back 169 years Integrates developmental, molecular, functional, experimental and palaeontological studies Documents the fate of the notochord across the vertebrates Extensively illustrated with classical and new images Related Titles Bard, J. Evolution: The Origins and Mechanisms of Diversity (ISNB 978-0-3673-5701-6) Leys, S. and Hejnol. A. Origin and Evolution of Metazoan Cell Types (ISBN 978-1-1380-3269-9)

Although it is the defining organ of Chordates, the notochord is perhaps the least understood of vertebrate organs because it is usually considered a transient structure only present in early embryonic development. Most tetrapods replace the notochord with cartilaginous or bony vertebral bodies and remnants of the notochord persist as intra- or intervertebral spaces and intervertebral discs. The presence of cartilage in the notochord of some tetrapods raises further important questions on the evolutionary relationships between notochordal cells and cartilage cells. This book explores these patterns of relationships between the notochord and vertebral axial chondrogenesis.

Animal life, now and over the past half billion years, is incredibly diverse. Describing and understanding the evolution of this diversity of body plans - from vertebrates such as humans and fish to the numerous invertebrate groups including sponges, insects, molluscs, and the many groups of worms - is a major goal of evolutionary biology. In this book, a group of leading researchers adopt a modern, integrated approach to describe how current molecular genetic techniques and disciplines as diverse as palaeontology, embryology, and genomics have been combined, resulting in a dramatic renaissance in the study of animal evolution. The last decade has seen growing interest in evolutionary biology fuelled by a wealth of data from molecular biology. Modern phylogenies integrating evidence from molecules, embryological data, and morphology of living and fossil taxa provide a wide consensus of the major branching patterns of the tree of life; moreover, the links between phenotype and genotype are increasingly well understood. This has resulted in a reliable tree of relationships that has been widely accepted and has spawned numerous new and exciting questions that require a reassessment of the origins and radiation of animal life. The focus of this volume is at the level of major animal groups, the morphological innovations that define them, and the mechanisms of change to their embryology that have resulted in their evolution. Current research themes and future prospects are highlighted including phylogeny reconstruction, comparative developmental biology, the value of different sources of data and the importance of fossils, homology assessment, character evolution, phylogeny of major groups of animals, and genome evolution. These topics are integrated in the light of a 'new animal phylogeny', to provide fresh insights into the patterns and processes of animal evolution. Animal Evolution provides a timely and comprehensive statement of progress in the field for academic researchers requiring an authoritative, balanced and up-to-date overview of the topic. It is also intended for both upper level undergraduate and graduate students taking courses in animal evolution, molecular phylogenetics, evo-devo, comparative genomics and associated disciplines.

The zebrafish is the most important fish model in developmental and genetic analyses. This book contains 19 review articles covering a broad spectrum of topics, from development to genetic tools. The contents range from early development, the role of maternal factors and gastrulation, to tissue differentiation and organogenesis, such as development of the organizer, notochord, floor plate, nervous system, somites, muscle, skeleton and endoderm. The genetic tools cover morpholino knock-down, transgenics, fish cloning, transposons and genome evolution. The book also includes two chapters on genome mapping and embryonic stem cells in medaka, another important model fish. Summarizing the state-of-the-art studies of the zebrafish model and focusing on the molecular aspects of development, this book is a valuable reference for students learning the basic aspects of the zebrafish model, and for researchers seeking resources in zebrafish research.

Depending on your point of view the brain is an organ, a machine, a biological computer, or simply the most important component of the nervous system. How does it work as a whole? What are its major parts and how are they interconnected to generate thinking, feelings, and behavior? This book surveys 2,500 years of scientific thinking about these profoundly important questions from the perspective of fundamental architectural principles, and then proposes a new model for the basic plan of neural systems organization based on an explosion of structural data emerging from the neuroanatomy revolution of the 1970's. The importance of a balance between theoretical and experimental morphology is stressed throughout the book. Great advances in understanding the brain's basic plan have come especially from two traditional lines of biological thought-- evolution and embryology, because each begins with the simple and progresses to the more complex. Understanding the organization of brain circuits, which contain thousands of links or pathways, is much more difficult. It is argued here that a four-system network model can explain the structure-function organization of the brain. Possible relationships between neural networks and gene networks revealed by the human genome project are explored in the final chapter. The book is written in clear and sparkling prose, and it is profusely illustrated. It is designed to be read by anyone with an interest in the basic organization of the brain, from neuroscience to philosophy to computer science to molecular biology. It is suitable for use in neuroscience core courses because it presents basic principles of the structure of the nervous system in a systematic way.