Reproduction is the origination of new organisms from pre-existing ones. Among more than 35 separated forms of reproduction including several types of gamogony, parthenogenesis, agamogenesis, fission and division, and plas motomy, the bisexual mode of reproduction via fertilization provides genetic variability that allows species to adapt quickly to competitive and constantly changing environments. Several excellent reviews and books have been written in the past to analyse the mechanisms of fertilization in different eukaryotic species. During the last few years, however, renewed attention has been paid to examining the process of oocyte fertilization at the cellular/molecular level not only within a single species/group but also through different phylogenetic lineages. As a result of this effort, knowledge of the molecular pathways used by oocytes and spermatozoa at fertilization has increased, but still many ques tions remain to be answered. Being aware of the necessity of providing an inte grated view of the process of fertilization, this book has been entirely devoted to reviewing the process of oocyte fertilization at the cellular/molecular level in two different and separated groups of eukaryotic organisms: protozoa and metazoan animals. The book is organized into six sections dealing with oocyte fertilization in protozoa, invertebrates, teleost fishes, amphibians, birds and mammals. These sections are followed by a summary/concluding chapter that provides a com parative overview of the process of fertilization in these groups of eukaryotes."

Ecology is characterized by a rapidly growing complexity and diversity of facts, aspects, examples, and observations. What is badly needed is the development of common patterns, of rules that, as in other sciences such as physics, can more generally explain the increasing complexity and variability we observe. Tom White, being one of the "seniors" in ecology, makes such an attempt in his book. the pattern he shows and explains with numerous examples from the entire animal kingdom is a universal hunger for nitrogen, a misery that drives the ecology of all organisms. He advocates that the awareness of this fundamental role that the limitation of nitrogen plays in the ecology of all organisms should be as a much part of each ecologis's intellectual equipment as is the awareness of the fact of evolution by means of natural selection. His claim is that not "enery" but "nitrogen" is the most limited "currency" in the animal world for the production and growth of their young.

During the period August 5-9, 1992, and immediately preceding the 1992 Gordon Research Conference on Motile and Contractile Systems, the "Third International Conference on the Structure and Function of Ubiquitous Cellular Protein Actin" was held at the Emma Willard School in Troy, New York, under the title "ACTIN '92". This conference focused on the fundamental properties and cellular functions of actin and actin based microfilament systems. The first conference in this series was held in 1982, in Sydney, Australia, and hosted by Dr. Cristobal G. dos Remedios and Dr. Julian A. Barden, both from the University of Sydney (New South Wales, Austrailia). The second conference convened in Monza, Italy in June 1987, and was organized by Dr. Roberto Colombo, University of Milan (Italy). This third gathering of researchers devoted to the study of actin and actin-associated proteins was organized by Dr. James E. Estes, Albany Stratton V A Medical Center and Dr. Paul 1. Higgins, Albany Medical College, who were assisted by an Organizing Committee consisting of Dr. Edward D. Korn (National Heart, Lung and Blood Institute, NIH), Dr. Thomas P. Stossel (Massachusetts General Hospital), Dr. Fumio Matsumura (Rutgers University), and Dr. Stephen Farmer (Boston University). This meeting was dedicated to the many pioneering contributions of Professor Fumio Oosawa to the field of actin research.

The Henry Goldberg Workshops were set up to address the following goals: (1) To foster interdisciplinary interaction between scientists and cardiologists, identify missing links, and catalyze new ideas. (2) To relate basic microscale phenomena to the global, clinically manifested cardiac function. (3) To relate conceptual modeling and quantitative analysis to experimental and clinical data. (4) To encourage international cooperation so as to disperse medical and technological knowhow and lead to better understanding of the cardiac system. The first Henry Goldberg Workshop, held in Haifa in 1984, introduced the concept of interaction between cardiac mechanics, electrical activation, perfusion, and metabolism, emphasizing imaging in the clinical environment. The second Workshop, in 1985, discussed the same parameters with a slant towards the control aspects. The third Goldberg Workshop, held in the USA at Rutgers University in 1986, highlighted the transformation of the microscale activation phenomena to macroscale activity and performance, relating electrophysiology, energy metabolism, and cardiac mechanics. The fourth Goldberg Workshop, in 1987, continued the effort to elucidate the interactions among the various parameters affecting cardiac performance, with emphasis on the ischemic heart. The fifth Workshop, held in Cambridge, UK, in 1988, dwelt on the effects of inhomogeneity of the cardiac muscle on its performance in health and disease. The sixth Workshop highlighted the role of new modem imaging techniques, that allow us to gain more insight into local and global cardiac performance in cardiac research and clinical practice.

The understanding of parallel processing and of the mechanisms underlying neural networks in the brain is certainly one of the most challenging problems of contemporary science. During the last decades significant progress has been made by the combination of different techniques, which have elucidated properties at a cellular and molecular level. However, in order to make significant progress in this field, it is necessary to gather more direct experimental data on the parallel processing occurring in the nervous system. Indeed the nervous system overcomes the limitations of its elementary components by employing a massive degree of parallelism, through the extremely rich set of synaptic interconnections between neurons. This book gathers a selection of the contributions presented during the NATO ASI School "Neuronal Circuits and Networks" held at the Ettore Majorana Center in Erice, Sicily, from June 15 to 27, 1997. The purpose of the School was to present an overview of recent results on single cell properties, the dynamics of neuronal networks and modelling of the nervous system. The School and the present book propose an interdisciplinary approach of experimental and theoretical aspects of brain functions combining different techniques and methodologies.

The International Societyon Oxygen Transport to Tissue (ISOTT) was founded in 1973 "to facilitate the exchange of scientific information among those interested in any aspect of the transport and/or utilization of oxygen in tissues." Its members span virtually all disciplines, extending from various branches of clinical medicine such as anesthesiology, ophthalmology and surgery through the basic medical sciences of physiology and biochemistry to most branches ofthe physical sciences and engineering. The eighteenth annual meeting of ISOTT was held in 1990 for four days, from July 19 to 22, in the Sheraton Hotel in Townsville, Queensland, Australia. The usual ISOTT format, which was originated in 1985 by Dr. Ian Longmuir, was continued. Almost all presentations were posters with an accompanying, scheduled, brief, slide presentation and discussion. All posters remained in place for the entire four days of the meeting. There were no simultaneous sessions. Essentially all aspects of physiological transport were covered at this meeting with possibly somewhat more emphasis on methods and instrumentation. The editors gratefully acknowledge the photographic skills of Dr. Jens Hoper who took the group picture during the outing to Magnetic Island on July 21. We are also most grateful to Dr. Rod D. Braun of Evanston for his invaluable editorial assistance. This volume is the thirteenth in the Plenum series Oxygen Transport to Tissue.

During the past decade interest in the formation of complex disorderly patterns far from equilibrium has grown rapidly. This interest has been stim ulated by the development of new approaches (based primarily on fractal geometry) to the quantitative description of complex structures, increased understanding of non-linear phenomena and the introduction of a variety of models (such as the diffusion-limited aggregation model) that provide paradigms for non-equilibrium growth phenomena. Advances in computer technology have played a crucial role in both the experimental and theoret ical aspects of this enterprise. Substantial progress has been made towards the development of comprehensive understanding of non-equilibrium growth phenomena but most of our current understanding is based on simple com puter models. Pattern formation processes are important in almost all areas of science and technology, and, clearly, pattern growth pervades biology. Very often remarkably similar patterns are found in quite diverse systems. In some case (dielectric breakdown, electrodeposition, fluid-fluid displacement in porous media, dissolution patterns and random dendritic growth for example) the underlying causes of this similarity is quite well understood. In other cases (vascular trees, nerve cells and river networks for example) we do not yet know if a fundamental relationship exists between the mechanisms leading the formation of these structures.

Advances in Compararative and Environmental Physiology helps biologists, physiologists, and biochemists keep track of the extensive literature in the field. Providing comprehensive, integrated reviews and sound, critical, and provocative summaries, this series is a "must" for all active researchers in environmental and comparative physiology. Cellular volume and osmolality in animals is a well studied topic and this specific volume in the series provides the reader with a thorough grounding in this area of physiology. Consisting of two parts, the text discusses osmolality and volume control in terms of both inorganic and organic ions which as a result gives an excellent overview to those working and interested in this field.

I had the good fortune to first meet Gerald Kuchling in 1985 when attending a conference held at the CNRS research centre, the Centre d'Etudes Biologiques des Animaux Sauvages (CEBAS), which is a wonderful scientific field station tucked away in the Foret de Chize, not far from the southwest town of Niort in France. The topic of the meeting, which included many invited overseas scientists, was "Physiological Regulations as Adaptive Mechanisms", and it was superbly organised by Ivan Assenmacher and Jean Boissin who together edited the impor- tant volume of papers published from the meeting. My stay in Chize was, unfor- tunately, cut short as the wife of a very close colleague died on the night of the first day of the meeting and I had to return to Paris to assist with the funeral -but not before I had the chance to meet and talk with Gerald. He was presenting some of his work on a terrestrial tortoise (or turtle depending upon one's origins) - Testudo hermanni - a species that is now extremely rare in France but still relatively abundant in the then Yugoslavia. Gerald had been working in Yugoslavia, collecting blood samples from both males and females in an attempt to decipher details of its reproductive biology.

It is two years since a general meeting of the Gesellschaft fur Biologische Chemie first requested us to organize the 21 st Mosbach Colloquium on mammalian reproduction, and one year since we received final authorization to do so. The present volume contains the papers read at the Colloquium, but the discussions have been omitted because writing and proof reading them would have delayed the appearance of this volume for an unjustifiable long time. Besides, in most cases the discussion was of a relatively specific nature and we did not consider it essential, bearing in mind that the purpose of the Mosbach Col loquia is to provide advanced further education for the non specialist. One of us has referred to this and to the topical structure of the 21 st Colloquium in the introductory and final remarks. Helpful suggestions for organizing the program were made by some of the invited speakers, but the first important impulses VON BERSWORDT-WALLRABE, Dr. ELGER, Dr. came from Dr. GERHARDS, Dr. NEUMANN, and Dr. UFER to whom we here wish express our thanks. Thanks are also due to those whose donations, some of which were very generous, made it financially possible to organize the Colloquium. HEINZ GIBIAN July 1970 ERNST JURGEN PLOTZ Contents Introduction. H. GIBIAN (Berlin) 1 General Outline about Reproductive Physiology and its Developmental Background. A. JOST (Paris) .. 4 The Significance of Hormones in Mammalian Sex Differentia tion as Evidenced by Experiments with Synthetic Andro gens and Antiandrogens. W. ELGER, F. NEUMANN, H.

Invertebrate animals represent a diversity of solutions to life's challenges. Success in a wide range of environments has been achieved by an almost bewildering range of invertebrate body forms. These body forms are reflected in the wonderful diversity of their nervous systems. Despite this apparent diversity, studies of the development of invertebrates and vertebrates are yielding common themes at the molecular level. Likewise, the phenome non of neural regeneration is based upon properties intrinsic to neurons and responses to a remarkably conserved chemical lan guage. This monograph focuses on the diversity and commonal ity of responses to neural injury. The rough and tumble of life may frequently damage some part of the body, particularly the appendages or sensory sys tems. The nervous system is usually involved in repair of other body systems and often may itself require repair. Some animals are particularly successful in regenerating the nervous system or body parts. We particularly marvel at these feats of regeneration because we human beings are not particularly successful, despite our relatively long life and the advantages that would seem to accrue from such repair. It is no wonder that we would hope to learn the secrets of the more successful animals and strive to emulate them Mechanisms of neural regeneration are often more acces sible in invertebrates than in vertebrates because questions of specificity are more easily addressed using the identifiable neu rons of the relatively simpler nervous systems of some inverte brates."

During the past decade there has been a dramatic expansion of our knowledge on phospholipases in general, and phospholipase A2 (PLA2) in particular. Progress in this field has been evident on many fronts, with novel information rapidly accumulating in the literature regarding the chemistry and molecular biology of this enzyme and its role in many important physiological processes. These include cellular signal transduction via the G-protein cycle, and in the generation of many cellular mediators, such as the platelet activating factor (PAF) and the eicosanoids that participate in the initiation and propagation of inflammation, to mention a few. This symposium was organized to obtain an overview of current investigations on this enzyme from the standpoint of its chemistry, molecular biology and physiology. Another important focus of this symposium concerns the regulation of PLA2, including endogenous and synthetic inhibitors and activators of this enzyme. To review these important areas in PLA2 research we invited scientists who made significant contributions in this field. The papers in this volume are organized to emphasize the recent advances in several areas of investigation, including: (I) the structure and mechanism of action of PLA2, (2) mechanism of activation of PLA2, (3) molecular biology, physiology and endogenous inhibitors of this enzyme and finally, (4) clinical investigations emphasizing the pathophysiological role of this enzyme in human diseases. The first article in this volume is by Dr.

Introduction to Mammalian Reproduction is a welcome contribution to the fields of gametogenesis, gamete transport, fertilization, and reproduction technologies. Key topics covered include:
*formation and maturation of male gametes;
*morphology and physiology of female gametes;
*how the sperm meets the egg;
*sperm-egg fusion, egg activation, and implantation of fertilized egg;
*assisted reproduction and environmental chemicals that have an effect on formation and function of male and female gametes. This book is for both researchers and students involved in reproductive biology.

This book includes articles relating to presentations given in a variety of forms (lectures, posters, contributions to round tables, software presentations) at the 5th International Biothermokinetics Meeting held in Bordeaux-Bombannes, September 23-26, 1992. The fact that not just lectures were considered for these proceedings reflects the aims of BTK meetings to instigate discussion, promote scientific cooperation and confront as many different ideas as possible with each other (at best heretical ones). BTK conferences have expanded more and more; 130 participants came to the 1992 meeting from 20 countries. It was therefore necessary to hold the round tables in parallel sessions. It is difficult to have an unbiased feeling of what should be selected as the salient features of the meeting. As the name suggests, Biothermokinetics embraces thermodynamic and kinetic approaches to experimental and theoretical investigations of biological processes, in particular at the cellular level. This "classical" point of view is mainly represented in the chapter "Thermodynamics and Kinetics of Transport Processes and Biological Energy Transduction."

The Association Internationale de Recherche sur la Circulation Osseuse, A.R.C.O., was founded in London in December 1989 by a small group of doctors, surgeons and researchers in basic sciences who had been involved for many years in the study of bone circulation and its disorders. They had met several times in Toulouse, during the International Symposia on Bone Circulation held there since 1973 and they wished to carry their contacts further. In founding A.R.C.O., they established as their primary aims the encouragement and furtherance of research, organisation of meetings and promotion of knowledge on the subject. At the present time, the Association has over a hundred members from more than bone tissue twenty countries in Europe, America and Asia. All have the conviction that and its pathology can only be truly known and studied if one has an understanding of its vascular system and the way its circulation functions. This concept, apparently beyond question, has not yet been adopted by all physicians and scientists who are interested in bone. From time to time, one comes across teaching programmes on bone patho logy which make no mention of bone circulation.

Similarities in structure and function between pigs and human beings include size, feeding patterns, digestive physiology, dietary habits, kidney structure and function, pulmo nary vascular bed structure, coronary artery distribution, propensity to obesity, respiratory rates, tidal volumes and social behaviors. Since the pig is an omnivore, it provides an adaptable model to evaluate chronic and acute exposures to xenobiotics such as alcohoL caffeine, tobacco, food additives and environmental pollutants. Swine have been used successfully as models to evaluate alcoholism, diabetes, absorption, digestion, total paren teral nutrition, organ transplantation, atherosclerosis, exercise, hypertension. hemorrhagic hypotension, melanoma, gingivitis, obstructive and reflux nephropathy. osteochondrosis. dermal healing and septic shock. A severe and worsening shortage of organs and tissues for transplantation in patients with severe organ failure has encouraged the consideration of inter species or xenotransplan tation. In developing programs toward this end, the pig generally is viewed as the preferred donor because of its size, physiology and availability. The pig harbors relatively few diseases which could be transmitted inadvertently to human patients. The ability to genetically modify swine to ameliorate the consequences of the human immune response offers a further significant advantage. Another important consideration for an animal model is that basic biologic back ground information be available for investigators to design future prospective studies."

Understanding how the brain works is undoubtedly the greatest challenge for human intelligence and one of the most ambitious goals of contemporary science. We are certainly far from this goal, but significant advancements in several fields of Neuroscience and Neurobiology are being obtained at an increasing pace. The NATO ASI School in Neurobiology, held in Erice May 2-12,1995, as the 23rd Course of the International School of Biophysics, provided an update on three basic topics: Biophysics and Molecular Biology ofIon Channels, Sensory Transduction, and Higher Order Functions. Current knowledge on these subjects was covered by formal lectures and critical discussions between lecturers and participants. This book collects original contributions from those scientists who attended the School. Many students presented their results in poster sessions, steering lively informal discussions. A selection of these contributions is also included. A major portion of the program of the School was devoted to a general overview of current trends of thought and experimental approaches in neurobiology, emphasising the importance of understanding molecular aspects of the elementary events underlying sensory transduction and processing in the nervous system, without indulging however in a pure reductionistic view of such complex phenomena. Recent studies of molecular biology and the electrophysiology of heterologously expressed ionic channels, have shed new light on the molecular mechanisms underlying ionic permeation of excitable membranes and its regulation by physical and chemical parameters.

The aimoftheHypospadiasand Genital Symposium, held at theUniversityof California,SanFrancisco,wastoprovideaforumforauthoritativeinvestigatorswhoare activelyinvolvedinthevariousdisciplineswhichdefinetheleadingedgesofhypospadias and genital research. It is important for such investigators to continue to meet for the purpose of discussing the latest developments in their individual fields, to analyze the significanceofcurrent research, to discuss new tactics for unresolved problems and to develop new theories andapproaches asneeded. The two day conference on hypospadiasandgenitaldevelopment research was organizedintothreesections: 1)HumanStudies;2)MechanismofGenitalDevelopment; and 3) Endocrine Disruptors and Sexual Dimorphism in the Animal Kingdom. Each sessionwasintroducedbyanexpertmoderatorfollowedtheinvitedspeakerswithtimefor extensiveinteractionbetweeninvestigators. Thisbookdocumentstheproceedingsofthe HypospadiasandGenitalDevelopmentSymposium. Iwould especially like to thank Kari Gaudette for editorial assistants, Cynthia Ashe, Selcuk Yucel, Antonio Souza and the administrative staffinthe Departmentof Urology. Ihopeyoufindthisresourceuseful. Laurence S. Baskin,M. D. ProgramChair ChiefPediatricUrology UCSF vii ACKNOWLEDGEMENTS Supportforthissymposiumisgratefullyacknowledged TheNationalInstituteofHealthGrant#R13DK*HDS997 UCSFDepartmentofUrology AmericanUrologicAssociation CONTENTS Introduction...1 SECTIONI. HUMANSTUDIES EpidemiologyofHypospadias...*...*...25 J. DavidErickson EndocrineEvaluationofHypospadias...31 G. HyunandT. Kolon EndocrineAbnormalitiesinBoyswithHypospadias...45 R. I. Silver GeneticandClinicalStudiesonHypospadias...***...**...*...73 A. Nordenskjold SECTIONII. MECHANISMOFGENITALDEVELOPMENT DevelopmentofthePenileUrethra. . 87 G. CunhaandL. Baskin AnatomicalStudiesoftheMouseGenitalTubercle...103 L. Baskin,W. Liu,J. Bastacky,andS. Yucel AnatomicalStudiesoftheFibroblastGrowthFactor-l0Mutant,Sonic HedgeHogMutant,andAndrogenReceptorMutantMouseGenital Tubercle...*. **. . 123 S. Yllcel,W. Liu,DCordero,A. Donjacour,G. Cunha,andL. Baskin DevelopmentalGeneticsofHypospadias...149 M. Cohn xiii xiv Contents DevelopmentoftheMouseExternalGenitalia: UniqueModelof Organogenesis...159 K. Suzuki, K. Shiota,Y. Zhang,L. Lei,andG. Yamada NewConceptsontheDevelopmentoCtheVagina...173 E. Shapiro. H. Huang,andX. R. Wu SECTIONIII. ENDOCRINEDISRUPTORSANDSEXUAL DIMORPHISMINTHEANIMALKINGDOM EndocrineDisruptionOverview: AreMalesatRisk? 189 T. Colburn EndocrineDisruptionandHypospadias...203 G. Steinhardt Toxicant-InducedHypospadiasintheMaleRat * 217 L. E. Gray. . I. Ostby,J. Fun,C. Wolf,C. Lambright,V. Wilson, and N. Noreiga MasculinizationofFemaleMammals: LessonsfromNature...243 N. J. PI:H'candS. Glickman Index...255 SectionI Introduction HYPOSPADIAS LaurenceS. Baskin* M. D. ,FAAP 1.

Since its inception in 1973, The International Society on Oxygen Transport to Tissue (ISOTT) has provided a unique forum to facilitate and encourage scientific interaction and debate. Welcoming scientists and clinicians from a broad spectrum of disciplines, each with their own particular skills and expertise, ISOTT unites them under the common theme of oxygen transport. The successful blend of scientific presentations and informal discussion which characterizes ISOTT is epitomized best by the many fundamental discoveries and technical advancements which it has spawned. The breadth and strengths of The Society's scientific base promotes the rapid progression of ideas from theoretical concepts to rigorous scientific testing and often, ultimately to the clinical arena. Each publication of the ISOTT proceedings has been recognized by Science Citation Index listing and the papers frequently establish scientific precedents and become considered as standard works in their respective fields. The 21st ISOTT Meeting was held in San Diego from August 14th through August 18th, 1993. The San Diego Meeting attracted about 150 registrants and 40 accompanying persons. Ten state-of-the-art lectures were presented by international experts in ~ transport and there were in addition two symposia -one dealing with assessment of tissue hypoxia and the other with functional heterogeneity in different organ systems. There were 100 free communications, consisting of posters accompanied by an abbreviated oral summary. All manuscripts were reviewed by the Editors for form and content, but as is customary for the ISOTT proceedings, rigorous scientific peer review was not undertaken.

It has been great fun to write this book, even though it has taken longer than planned, and occasionally been exasperating. The most difficult problem was deciding what to exclude among so many interesting things, because the available material usually exceeded the space. Because a book like this covers so many aspects, each component must be limited. This book is intended for graduate and undergraduate students as well as professional scientists who want to work with animal flight or to gain some insight into flight mechanics, aerodynamics, energetics, physiology, morpho logy, ecology and evolution. My aim has not been to give the whole mathe matical explanation of flight, but to provide an outline and summary of the main theories for the understanding of how aerofoils respond to an airflow. I also hope to give the reader some insight into how flight morphology and the various wing shapes have evolved and are adapted to different ecological niches and habitats."

I have spent less time in the arid zone in the last few years than I did during the 1960's, 1970's and early 1980's. This results from a progression through age and a career structure which gradually shifted the emphasis of my work from being essentially field-oriented to essentially office-hound. When, therefore, I was asked by John Cloudsley-Thompson to undertake the writing of this hook I hesitated for two reasons. One reason was that, although I now had access to good library facilities and kept up with the literature on the arid zones and their fauna, I was not sure that a sedentary and pleasant life in a temperate highland island in tropieal Africa would provide a mental attitude suitable to writing a hook which related to areas where life is usually nomadie and often extremely disagreeable. The other reason was that I was uncertain whether I could devote the time necessary to researehing and writing the hook on top of my professional (which now specifical ly excluded research in the arid zones and on camels) and social (new-found and time-consuming) commitments. In the event I accepted and the fates were kind to me. By some peculiar combination of circumstances I was given the opportunity to spend a considerable part of the first half of 1988 in some of the driest areas of the globe. I had already visited all of the locations used for the construction of Fig. 2."

The research field of somatosensory processing in mammals has experienced revolutionary changes in recent years. Accumulation of basic and clinical data has greatly accelerated, and new phenomena have emerged. With the aid of new, refined methods, molecular and cellular changes have been described, underlying the signal transduction-transmission between the internal/external environment and the central nervous system have been described. The discovery of the interaction between the nervous and the immune system has, for example changed our view on the development of inflammatory diseases, while the cloning of genes encoding different trophic factors has boosted studies revealing profound changes in the regeneration of neurons, and induction of changes in phenotype. The study of the pre-and postsynaptic modulation of transmitter release, and the examination of the combined effects of amino acid and peptide transmitters has become recently possible by using cultured cell lines and in vitro techniques. Although it is in embryonic state, computational properties of single DRG cells under normal and pathological conditions are being investigated. Results soon or later will have a great impact on pain research and consequently ultimately in clinical pain management. This brief introduction indicates how our knowledge of the somatosensory system has increased dramatically recently. However, many investigators cultivate only a very specific field in the growing area of somatosensory research and find it difficult to integrate a more universal knowledge of their work.

Experimental approaches to auditory research make use of validated animal models to determine what can be generalized from one species to another. This volume brings together our current understanding of the auditory systems of fish and amphibians. To address broader comparative issues, this book treats both fish and amphibians together, to overcome the differing theoretical and experimental paradigms that underlie most work on these groups.

Many organisms have evolved the ability to enter into and revive from a dormant state. They can survive for long periods in this state (often even months to years), yet can become responsive again within minutes or hours. This is often, but not necessarily, associated with desiccation. Preserving one's body and reviving it in future generations is a dream of mankind. To date, however, we have failed to learn how cells, tissues or entire organisms can be made dormant or be effectively revived at ambient temperatures. In this book studies on organisms, ranging from aquatic cyanobacteria that produce akinetes to hibernating mammals, are presented, and reveal common but also divergent physiological and molecular pathways for surviving in a dormant form or for tolerating harsh environments. Attempting to learn the functions associated with dormancy and how they are regulated is one of the great future challenges. Its relevance to the preservation of cells and tissues is one of the key concerns of this book.

The field of olfactory research and chemical communication is in the early stages of revolutionary change, and many aspects of this revolution are reflected in the chapters in this book. Thus, it should serve admirably as an up-to-date reference. First, a wide range of vertebrate groups and species are represented. Second, there are excellent reviews of specific topics and theoretical approaches to communication by odors, including chapters on signal specialization and evolution in mammals, the evolution of hormonal pheromones in fish, alarm pheromones in fish, chemical repellents, the chemical signals involved in endocrine responses in mice, and the controversy over human pheromones. Third, there are exciting new findings presented in numerous specific topic areas, such as the chemis try of pheromones in a wide range of species (salamanders to elephants), the chemistry of proteins that control the release of pheromones, the molecular biology and physiology of detection, coding and response to odor signals, the effects of experience on sensitivity to odors, the role of genes of the immune system in odor production and in human mate choice, the function and perception of scent over-marks, the recognition of individuals and kin by odors, the influence of odors on predator-prey interactions, and the use of odors to help control pests. This book is an offshoot of the Eighth International Symposium on Chemical Sig nals in Vertebrates, held at Cornell University in Ithaca, New York, July 20-25, 1997, hosted and organized by Bob Johnston.