In this issue of Current Topics in Microbiology and Immunology the authors present a unique range of examples of the regenerative response and the role of stem cells from the amphibian to human. It seems that all roads lead to cells that have the plasticity to become something else, not only in the amphibian but also in the mammal.

This volume discusses recent advances in avian and reptilian biology that have caused this diverse field to re-emerge. The chapters in this book are divided into 4 parts: genomics and transcriptomics, genetic manipulation, stem cells, and new model systems. Part I details how to perform genomic and transcriptomic analyses in birds and reptiles; Part II highlights technological advancements in avian genetic manipulation; Part III focuses on methods to handle pluripotent cells; and part IV looks at the emerging models in avian and reptilian developmental biology. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Cutting-edge and comprehensive, Avian and Reptilian Developmental Biology: Methods and Protocols explores a var iety of approaches and different sauropsid models that will help facilitate communication and collaboration among researchers, which in turn will progress this field forward.

For anybody capable of an emotional response to it, any view of a developing organism should give birth to a feeling of amazement and even admiration, whether this development is seen directly, or in the form of a time lapse film, or even if mentally reconstructed from a series of static images. We ask ourselves how such seemingly primitive eggs or pieces of tissue, without any obvious intervention from outside, so regularly transform themselves into precisely constructed adult organisms. If we try to formulate what amazes us most of all about development, the answer will probably be that it is the internal capacity of developing organisms themselves to create new structures. How, then, can we satisfy our amazement in ways that are more or less reasonable, as well as scientifically valuable? This depends, first of all, on what position we choose to regard embryonic development as occupying among other structure creating processes, even including human activities. On the one hand, one might regard the development of organisms as a highly specialized class of processes, unique to themselves and alien to the general laws of nature, or at least not derivable from them and more akin to the deliberate acts of our own human behaviour. In that case our task would become reduced to a search for some specific 'instructions' for each next member of such a class. Whether in an overt or hidden form, some such ideology seems to dominate in present day developmental biology.

Ionizing Radiation and the Immune Response, Part B, Volume 378 reviews the latest knowledge on the immune response induced by ionizing radiations. Specific chapters in this new release include NK functions in radio-induced immune response, TRT and immune response, Radio-induced immune response and lipid metabolism, Effect of protons and heavy ions on immune response, Effect of flash therapy and mini beam on immune response, Radio-induced lymphopenia, CT to potentiate radio-induced immune response, Impact of RT on healthy tissues (inflammation), Radio-induced macrophagic response, To use nanoparticles and ionizing radiations to modulate immune response: opinion of the chemist, biologist and clinician, and much more. Other sections cover the Role of Dendritic cells in radiation-induced immune response, the Relationship between the tumor microenvironment and the efficacy of the radiotherapy/immunotherapy combination, and Biomarkers of radiation induced response to optimize radio-immunotherapy combination.

Zebrafish are widely considered an excellent modelsystem for vertebrate development. The embryo is transparent, thereby enabling visualization and use of labelling and transgenic approaches. Moreover, because of the ease of inducing new mutations in zebrafish and similarity with the human genome, this organism may be used effectively for disease studies. For example, mutant zebrafish are being utilized for testing drugs that will combat a range of human diseases, from Alzheimer's and cancer to kidney failure and congenital heart disease. For the first time, this atlas provides the research community with a complete reference for zebrafish anatomy spanning the early embryo all the way to adulthood.
The authors employ the technique of optical projection tomography (OPT), and offer a series of sections in multiple planes from each sample. The contents are organized by developmental stages, with over 200 images that contain annotations describing anatomical structures relevant to development. In addition, chapters feature explanatory text that highlights major developments in the zebrafish during each stage.
* Provides the first comprehensive anatomical resource that covers all regions of zebrafish anatomy from the larval period to adulthood.
* The over 200 images include explanatory notes
* Each chapter contains a concise description of key anatomical features that factor in zebrafish development
* Despite many years of use as a model system, until now there has never been a guide to zebrafish at the larval stage.
* The book's website contains a database of over 10k sections from different regions as well as 3D images that are interactive."

Stem cells have the ability to differentiate into all types of cells within the body, thus have great therapeutic potential for regenerative medicine to treat complicated disorders, like Parkinson s disease and spinal cord injury. There will also be many applications in drug development. However, several roadblocks, such as safety issues and low efficiency of pluripotent stem cell (PSC) line derivation need to be resolved before their clinical application. This thesis focuses on these two areas, so as to find methods to overcome the limitation. It covers deriving embryonic stem cells (ESCs) from several different species and reports an efficient system to generate induced pluripotent stem cells (iPSCs), and the first iPSC mice in the world. The results in this thesis confirm that somatic cells can be fully reprogrammed with the four Yamanaka factors. In addition, we have found that the Dlk1-Dio3 region can be a potential molecular marker to distinguish the fully reprogrammed iPSCs from partially reprogrammed ones. All of these results will help improve the safety of PSCs in the clinical applications and increase the current low induction efficiency of their production."

Some Problems in Limb Development.- The Molecular Basis of Limb Patterning: A Review.- Expression of the Msh-like Homeobox-containing Genes During Mouse Limb Development.- The Limb Deformity Gene Encodes Evolutionarily Highly Conserved Proteins.- The Role of Homeobox Genes in Amphibian Limb Development and Regeneration.- Homeobox-Containing Genes and Gap Junctional Communication in Pattern Formation During Chick Limb Development.- Functional Studies of Genes in the Limb.- Hox-7: Temporal Patterns of Expression in Normal and Limbless Chick Embryos.- Expression Profile of Two Homeobox Genes During Chicken Embryogenesis.- Characterisation of Three Zebrafish Genes Related to Hox-7.- A Comparison of the Expression Domains of the Murine Hox-4, RARs and CRABP Genes Suggest Possible Functional Relationships During Patterning of the Vertebrate Limb.- Retinoic Acid Nuclear Receptors.- The Role of Retinoic Acid and Cellular Retinoic Acid-Binding Protein in the Regenerating Amphibian Limb.- Retinoic Acid Treatment Alters the Pattern of Retinoic Acid Receptor Beta Expression in the Embryonic Chick Limb.- Expression Pattern of an RXR Nuclear Receptor Gene in the Chick Embryo.- Retinoic Acid and Limb Pattern Formation in Cell Culture.- Growth Factors Produced by the Polarising Zone - a Complement to the Retinoic Acid System.- Biochemical and Molecular Aspects of Retinoid Action in Limb Pattern Formation.- Position-Dependent Properties of Limb Cells.- Retinoic Acid and Limb Patterning and Morphogenesis.- Does Retinoic Acid Organise a Limb or Induce a ZPA?.- Retinoic Acid Effects on Experimental Chick Wing Buds: Patterns of Cell Death and Skeletogenesis.- A Comparison of Reaction Diffusion and Mechanochemical Models for Limb Development.- The Pathway of Polarising Activity from Hensen's Node to the Wing Bud in the Chick Embryo.- Extracellular Matrix in Early Limb Development.- Molecular Heterogeneity of Chondroitin Sulphate in the Developing Chick Limb.- Special Properties of the AER/Mesenchyme Interface in the Chick Wing Bud: Analysis of ECM Molecules and Integrin Receptors.- Physical Forces and Pattern Formation in Limb Development.- Extracellular Material Organization and Long Tendon Formation in the Chick Leg Autopodium. In Vivo and In Vitro Study.- Hyaluronan-Cell Interactions in Limb Development.- The Role of the Transforming Growth Factor-ss (TGF-ss) Family, Extracelluiar Matrix and Gap Junctional Communication in Limb Cartilage Differentiation.- Vascular Involvement in Cartilage and Bone Development.- Patterning of Connective Tissues in the Regenerating Amphibian Limb.- The Interdigital Spaces of the Chick Leg Bud as a Model for Analysing Limb Morphogenesis and Cell Differentiation.- A "Packaging Model" of Limb Development.- The Somite-Muscle Relationship in the Avian Embryo.- Observations Concerning the Control of Directed Myogenic Cell Migration.- Extracellular Matrix and Muscle Formation.- Control of Muscle Morphogenesis and Endplate Pattern in Limb Muscles of Avian Chimeras.- Review of the Extracellular Matrix in Relation to Limb Development.- Evolution of Connective and Skeletal Tissues.- Developmental Approaches to the Problem of Transformation of Limb Structure in Evolution.- New Palaeontological Contributions to Limb Ontogeny and Phylogeny.- The Fin-Limb Transformation: Palaeontological and Embryological Evidence.- The Development of the Teleost Fin and Implications for our Understanding of Tetrapod Limb Evolution.- Phylogenetically Ancient Pattern in Ontogenesis of Limb Muscles.- Mutation and Limb Evolution.- Insights into Limb Development and Pattern Formation from Studies of the Limbless and Talpid2 Chick Mutants.- Proximal Elements in the Vertebrate Limb: Evolutionary and Developmental Origin of the Pectoral Girdle.- Evolutionary Transformation of Limb Pattern: Heterochrony and Secondary Fusion.- Plasticity in Skeletal Development: Knee-Joint Morphology in Fibula-Deficient Chick Embryos.- The Implications of "The Bauplan" f

The organizer area plays a central role in the formation of the embryonic axis and the central nervous system of all vertebrates including the human fetus. In The Vertebrate Organizer, outstanding molecular development biologists and embryologists report their latest approaches in this fascinating research area using different vertebrate model organisms. The presented data is of central importance for the understanding of early human embryogenesis.

Few, if any, genes have had the same level of impact on the field of evolutionary-developmental biology (evo-devo) as the Hox genes. These genes are renowned for their roles in patterning the body plans and development of the animal kingdom. This is complemented by the distinctive organisation of these genes in the genome, with them frequently being found as clusters in which gene position is linked to when and where the individual genes are expressed, particularly during embryogenesis. This book provides the latest overviews of Hox gene organisation and function for major clades of animals from across the animal kingdom. With the rapidly increasing availability of high-quality whole genome sequences from an ever-expanding range of species, it is becoming increasingly evident that there is great diversity in the organisation of Hox genes. These great strides in genome sequencing are wedded to important developments in our ability to detect expression and disrupt gene function in species that are not traditionally genetically-amenable animals. These technical developments are integrated with wide taxon-sampling in this volume to provide new perspectives on the roles of Hox genes in understanding fundamental issues such as embryo patterning, mechanisms of gene regulation, homology, evolvability, evolutionary novelties, phylogeny, the role of gene and genome duplications in evolution, and ancestral states for major clades of animals. Key features Integrative overviews from major animal groups including, arthropods, vertebrates, echinoderms, mollusks and other spiralians. Perspectives gleaned from the latest genome sequence and gene expression data. Individual chapters written by world-leading experts in Hox genes and evo-devo in each animal group. Related Titles Scholtz, G., ed. Evolutionary Developmental Biology of Crustacea (ISBN 978-9-0580-9637-1) Mattick, J. & P. Amaral. RNA, The Epicenter of Genetic Information (ISBN 978-0-3675-6778-1) Bard, J. Evolution: The Origins and Mechanisms of Diversity (ISBN 978-0-3673-5701-6)

Ionizing Radiation and the Immune Response, Volume 376, Part A reviews the latest updates on the immune response induced by ionizing radiations. Sections discuss the role of specific immune cells (macrophage, lymphocyte, NK cells...) and describe the effect of modern radiotherapy techniques (TRT, minibeams, flash-RT, proton therapy, heavy ions...) on immune response. Sample chapters cover NK functions in radio-induced immune response, TRT and immune response, Radio-induced immune response and lipid metabolism, Effect of protons and heavy ions on immune response, Effect of flashtherapy and mini beam on immune response, Radio-induced lymphopenia, CT to potentiate radio-induced immune response, and much. Other sections focus on the Effect of low dose radiation on radio-induced immune response, Role of Dendritic cells in radiation-induced immune response, Relationship between the tumor microenvironment and the efficacy of the radiotherapy/immunotherapy combination+A23, Biomarkers of radiation induced response to optimize radio-immunotherapy combination.

Developmental biology is seemingly well understood, with development widely accepted as being a series of programmed changes through which an egg turns into an adult organism, or a seed matures into a plant. However, the picture is much more complex than that: is it all genetically controlled or does environment have an influence? Is the final adult stage the target of development and everything else just a build-up to that point? Are developmental strategies the same in plants as in animals? How do we consider development in single-celled organisms? In this concise, engaging volume, Alessandro Minelli, a leading developmental biologist, addresses these key questions. Using familiar examples and easy-to-follow arguments, he offers fresh alternatives to a number of preconceptions and stereotypes, awakening the reader to the disparity of developmental phenomena across all main branches of the tree of life.

This book provides an overview of the role and function of regulatory RNAs that lack protein-coding potential in key reproductive tissues. This includes the role of small interfering RNAs (siRNAs), microRNAs (miRNAs), PIWI-interacting RNAs (piRNAs), small nucleolar RNAs (snoRNAs) and long non-coding RNAs (lncRNAs). Through clear, detailed and comprehensive debate, international leading experts discuss the role these novel regulators in normal development of sexual dimorphisms, including the differentiation of ovaries and testes, the genital tract including prostate, epididymis and uterus, as well as mammary glands. In addition, particular attention is paid on their role in pathophysiological processes within the reproductive tract. The power of next generation sequencing has proved to be an invaluable tool to discover new non-coding RNAs. While the identification of non-coding RNA is relatively easy, analysing their function represents still a challenge today. In this book, authors present historical and conceptual background information, highlight the ways in which non-coding RNAs function is analysed and present their vision of the future research in their key research area.

... an adult poet is simply an individual in a state of arrested development-in brief, a sort of moron. Just as all of us, in utero, pass through a stage in which we are tadpoles, ... so all of us pass through a state, in our nonage, when we are poets. A youth of seventeen who is not a poet is simply a donkey: his development has been arrested even anterior to that of the tadpole. But a man of fifty who still writes poetry is either an unfortunate who has never developed, intellectually, beyond his teens, or a conscious buffoon who pretends to be something he isn't-something far younger and juicier than he actually is. -H. 1. Mencken, High and Ghostly Matters, Prejudices: Fourth Series (1924) Where would evolution be, Without this thing, heterochrony? -M. L. McKinney (1987) One of the joys of working in a renascent field is that it is actually possible to keep up with the literature. So it is with mixed emotions that we heterochronists (even larval forms like myself) view the recent "veritable explosion of interest in heterochrony" (in Gould's words in this volume). On the positive side, it is ob viously necessary and desirable to extend and expand the inquiry; but one regrets that already we are beginning to talk past, lose track of, and even ignore each other as we carve out individual interests."

Cilia: From Mechanisms to Disease, Part A, Volume 175 in the Methods in Cell Biology series, offers a range of techniques and protocols that can be used to study aspects of this interesting cellular organelle both in vitro and in vivo. In this volume, different study models are used, such as human cell lines, Mus musculus, Danio rerio, Paramecium caudatum or Chlamydomonas reinhardtii. Besides, protocols to study the genesis, morphology, composition and function of cilia will be addressed. In this book, the ciliary study will be realized by using different techniques such as flow cytometry, time-lapse images of fluorescent ciliary proteins, the use of organoids, the evaluation of the ciliary-GPCR dynamics or genetic modulation by using CRISPR/Cas9.

Myeloid-Derived Suppressor Cells, Volume 378, includes comprehensive and detailed reviews on the current advances in myeloid derived suppressor cells, an immature, heterogenous cell population from the myeloid lineage that has been extensively described in the last decades due to its potent immunosuppressive activity in a variety of pathologies. Reviews maintain a high standard by publishing invited articles on important and timely topics authored by prominent researchers. The articles published in IRCMB have a high impact. IRCMB ranks high amongst scientific journals dealing with cell biology.

This book presents a timely collection of reviews by experts in periconception and fertilization. The book provides a good introduction for those new to the field as well as those who have worked in this field for some time, but not have been able to keep up-to-date with recent advances on the topic. The book reviews the current knowledge in this field, then focuses its attention on short-term and long-term effects of the periconception period, both from a physiological and medical perspective. Finally the volume covers the examination of the potential mechanisms involved in controlling periconception period. From the early days of discovery about the basics of the fertilization process, scientists have known that early events happening during conception play a major part in the creation of new offspring. However, until nearly a decade ago we thought these events were just concerned with the conception and nothing to do with lifelong health and welfare, or wellbeing of the offspring. Early indications from IVF in sheep and cattle suggested that the embryo culture conditions employed in the laboratory could result in unusually large and unhealthy offspring. These observations sounded alarm bells and stimulated research into the impacts of in vivo and in vitro conditions on the health of embryos and offspring. This book provides a summary of the state-of-the-art research being done to more fully understand the importance of the periconception environment.

Complexity increases with increasing system size in everything from organisms to organizations. The nonlinear dependence of a system's functionality on its size, by means of an allometry relation, is argued to be a consequence of their joint dependency on complexity (information). In turn, complexity is proven to be the source of allometry and to provide a new kind of force entailed by a system's information gradient. Based on first principles, the scaling behavior of the probability density function is determined by the exact solution to a set of fractional differential equations. The resulting lowest order moments in system size and functionality gives rise to the empirical allometry relations. Taking examples from various topics in nature, the book is of interest to researchers in applied mathematics, as well as, investigators in the natural, social, physical and life sciences. Contents Complexity Empirical allometry Statistics, scaling and simulation Allometry theories Strange kinetics Fractional probability calculus

In 1964, the Fertilization and Gamete Physiology Research Training Program (FERGAP) was established at the Marine Biological Laboratories, Woods Hole, Massachusetts. Over the course of the next 12 years, under the directorship of Dr. Charles B. Metz, FERGAP brought together, trained, and inspired a generation of students in reproductive biology from all over the world. As students of C. B. Metz and as FERGAP trainees, we would like to dedicate this collected work on comparative mammalian fertilization to our teacher and mentor, Dr. Charles B. Metz. Like a number of authors contributing to this volume, we have been struck by the significant impact that C. B. Metz and FERGAP had on the development of students of reproductive biology. Applying both the classical and molecular techniques of cell biology and immunology to problems of gamete biology, Dr. Metz emphasized a comparative and analytical approach that was reflected in his own research on fertilization in Paramecia, sea urchins, frogs, and mammals. It is hoped that this volume will serve to stimulate students to discover the myriad of fascinating research problems in gamete and reproductive biology. Bonnie S. Dunbar Michael G. O'Rand Houston, Texas Chapel Hill, North Carolina ix Contents Part I COMPARATIVE OVERVIEW OF MAMMALIAN GAMETES The Coevolution of Mammalian Gametes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 J. Michael Bedford I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Gamete Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Monotremes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 . . . . . . . . . . . . . . 2.2. Marsupials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 . . . . . . . . . . . . . . . 2.3. Eutherians . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3. Gamete Maturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 . . . . . . . . . . . . . . . 3 .1. Oocyte Maturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 . . . . . . . . . . . . . 3.2. Sperm Maturation in the Male . . . . . . . . . . . . . . . . . . . . . . . 15 . . . . . . . . . .

This detailed volume compiles numerous methods to explore fly oogenesis. Beginning with updated protocols from isolating and staining the ovary to numerous imaging techniques and genetic protocols for cell-specific assessment and CRISPR-mediated mutagenesis, the volume continues by detailing techniques from assessing cytoskeletal structures to uncovering protein-protein interactions, with closing chapters exploring how Drosophila oogenesis can be used in the classroom and in outreach programs to increase interest in biomedical research, STEM education, and STEM careers. Written for the highly successful Methods in Molecular Biology series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step and readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and practical, Drosophila Oogenesis: Methods and Protocols serves as an ideal guide for both new and expert researchers working with this robust and versatile model organism.

The overall scope of this new series will be to evolve an understanding of the genetic basis of (1) how early mesoderm commits to cells of a heart lineage that progressively and irreversibly assemble into a segmented, primary heart tube that can be remodeled into a four-chambered organ, and (2) how blood vessels are derived and assembled both in the heart and in the body. Our central aim is to establish a four-dimensional, spatiotemporal foundation for the heart and blood vessels that can be genetically dissected for function and mechanism. Since Robert DeHaan's seminal chapter "Morphogenesis of the Vertebrate Heart" published in Organogenesis (Holt Rinehart & Winston, NY) in 1965, there have been surprisingly few books devoted to the subject of cardiovascular mor phogenesis, despite the enormous growth of interest that occurred nationally and internationally. Most writings on the subject have been scholarly compilations of the proceedings of major national or international symposia or multiauthored volumes, often without a specific theme. What is missing are the unifying concepts that can make sense out of a burgeoning database of facts. The Editorial Board of this new series believes the time has come for a book series dedicated to cardio vascular morphogenesis that will serve not only as an important archival and didac tic reference source for those who have recently come into the field but also as a guide to the evolution of afield that is clearly coming of age.

The Immunological Synapse, Part A, Volume 173 in the Methods in Cell Biology series provides state-of-the-art methods for the study of the immunological synapse. Sections cover Imaging polarized granule release at the cytotoxic T cell immunological synapse using TIRF microscopy: control by polarity regulators, Analysis of centrosomal area actin reorganization and centrosome polarization upon lymphocyte activation at the immunological synapse, P815-based redirected degranulation assay to study human NK cell effector functions, Cytotoxic and Chemotactic Dynamics of Natural Killer Cells Quantified by Live-cell Imaging, Quantification of interaction frequency between antigen-presenting cells and T cells by conjugation assay, and more. Other chapters focus on the Study of the Effects of NK-Tumor Cell Interaction by Proteomic Analysis and Imaging, Quantification of lymphocytic choriomeningitis virus specific T cells and LCMV viral titers, Quantification of lymphocytic choriomeningitis virus specific T cells and LCMV viral titers, An in vitro model to monitor natural killer cell effector functions against primary breast cancer, and Standardized Protocol for the Evaluation of Chimeric Antigen Receptor (CAR)-modified Cell Immunological Synapse Quality using the Glass-supported Planar L.

1) Classic anatomical atlases 2) Detailed labeling of the earliest phases of prenatal neorological development 3) Appeals to neuroanatomists, developmental biologists and clinical practioners. 4) Persistent relevantce - brain development is not going to change.

Phenotypic plasticity - the ability of an individual organism to alter its features in direct response to a change in its environment - is ubiquitous. Understanding how and why this phenomenon exists is crucial because it unites all levels of biological inquiry. This book brings together researchers who approach plasticity from diverse perspectives to explore new ideas and recent findings about the causes and consequences of plasticity. Contributors also discuss such controversial topics as how plasticity shapes ecological and evolutionary processes; whether specific plastic responses can be passed to offspring; and whether plasticity has left an important imprint on the history of life. Importantly, each chapter highlights key questions for future research. Drawing on numerous studies of plasticity in natural populations of plants and animals, this book aims to foster greater appreciation for this important, but frequently misunderstood phenomenon. Key Features Written in an accessible style with numerous illustrations, including many in color Reviews the history of the study of plasticity, including Darwin's views Most chapters conclude with recommendations for future research

This book is the product of a NATO Advanced Study Institute of the same name, held at the Anargyrios and Korgialenios School on the island of Spetsai, Greece, in September 1994. The institute considered the molecular mechanisms which generate the body plan during vertebrate embryogenesis. The main topics discussed included: commitment and imprinting during germ cell differentiation; hierarchies of inductive cell interactions; the molecular functioning of Spemann's organizer and formation of embryonic axes; the extracellular matrix and the cytoskeleton in relation to morphogenesis and cell migration; neurogenesis and patterning of the neuraxis; the regulation of pattern formation by Hox genes and other transcription factors. This ASI was marked by a number of special features. An important one was that it brought together three different generations of embryologists: pioneers in classical embryology; scientists who are now leading the present molecular elucidation of vertebrate embryogenesis; and the promising younger ASI participants, some of whom are already making important contributions to this field. This aspect was very important in determining the character of the meeting. It exposed ambiguities in the classical embryological dogma and thus facilitated a subtle application of the recent molecular findings to classical problems. The second shining feature of this ASI was its evolutionary emphasis. The findings presented were obtained in four different vertebrate systems: mammals (the mouse), avians (the chicken), amphibians (Xenopus) and the teleost fishes (zebrafish).