This volume describes the proceedings of the Workshop Conference on The Human Testis which was held at Positano, Italy, April 23-25, 1970. The format of the book has been arranged according to topics discussed during the Conference. Each chapter includes individual contributions followed by discussion. Thus, this volume provides a current critical evaluation of the subjects discussed. The Editors assume responsibility for any shortcomings and wish to thank all par~ ticipants for their unprecedented cooperation in making this publi cation possible. The Editors are indebted to Miss Barbara Martin for her able secretarial and administrative assistance and to Mrs. Griff T. Ross who supervised the secretarial staff during the conference. Rec ognition is also due to Mrs. M. Flack for editorial assistance. The Workshop Conference could not have taken place but for the Serono Foundation, which supported this Meeting as well as the pub lication of the Proceedings of this Workshop. The physical as well as the technical arrangements were under the careful direction of Mr. Cesare Florimonte of the Serono Foundation. The support pro vided by the Serono Foundation is another proof of its generosity in stimulating scientific exchanges and a demonstration of its con tinuous efforts to support basic and applied studies in the field of human reproduction. We express our thanks to our Publisher, Plenum Press, for their fine cooperation and for ensuring the rapid publication of this vol ume.

This volume is an outgrowth of a symposium held at the University of Michigan, Ann Arbor, Michigan, October 27-29, 1975. This symposium was organized to bring together basic scientists and clinicians for the purpose of exchanging new ideas and the latest information in the area of Steroid Hormone Action and Cancer. The design of the symposium included both formal plenary sessions and informal roundtable discussion groups, the chapters of this volume being drawn primarily from these proceedings. During the last quarter of a century considerable progress has been made toward understanding the molecular mechanisms in volved in steroid hormone action. It now appears that the mechan sim of action of the four major classes of steroid hormones is qualitatively similar. Research during the past decade has demonstrated steroid hormone receptors in a variety of normal and neoplastic tissues. Receptor-containing neoplasms have been shown to be hormone-dependent and undergo regression when treated with hormone antagonists. Natural and synthetic steroids also have been employed for many years to successfully treat various types of cancer, for example: estrogens, androgens and progestagens for breast cancer; estrogens and progestagens for prostatic carcinoma; progestagens for endometrial carcinoma; and corticoids for leu kemias. All of these neoplasms have now been found to possess receptors for the steroids empirically used in their treatment."

As humans ventured into the twentieth century, the industrialized countries were confronted with the scourge of rickets. Although solariums were becoming common in the early 1900s and phototherapy was gaining popularity as a result of the awarding of a Nobel Prize to Finsen in 1903, it wasn't until 1921 when Hess and Unger demonstrated that rickets could be cured by exposure to sunlight that the healthful benefit of sun exposure appreciated. In 1941, Apperly (Cancer Research; 1: 191-195, 1941) noted that the occasional increased risk of skin cancer was associated with a decreased risk of many other more common and serious cancers. The alarming increase in the number of cases of skin cancer, especially melanoma, has caused great concern about the negative role of sunlight in health. The Sixth International Arnold Rikli Symposium on the Biologic Effects of Light was held in Boston, Massachusetts from June 16th - 18th, 2001. The goal of this Symposium was to focus on the very popular practice of tanning either by sunlight or by artificial light sources and the overall impact this practice has on health and disease. The program was organized by members of the Scientific Advisory Committee and my co-chair emeritus, Professor Ernst G. Jung. The Program Committee organized an outstanding state-of-the-art program that was enthusiastically received by the participants.

Diabetes continues to spread across the globe at an alarming rate, with a current count of approximately 386 million worldwide. Physicians and healthcare professionals in all specialties greatly need a concise guide for managing this disease on a daily basis.

"Diabetes Mellitus A Concise Clinical Guide" covers the basics of diagnosis, complications, therapies and prevention. Major developments in understanding diabetes and in therapeutic approaches to this disease are also featured. This book is comprised of sections originally published in the comprehensive textbook, "Principles of Diabetes Mellitus, Second Edition."

Primary care physicians and endocrinologists, as well as medical students, will find this guide an invaluable and practical reference."

The human pancreas consists of two organs in one: the exocrine gland made up of pancreatic acinar cells and duct cells that produce digestive enzymes and sodium bicarbonate, respectively; the endocrine gland made up of four islet cells, namely alpha-, beta-, delta- and PP-cells that produce glucagon, insulin, somatostatin and pancreatic polypeptide, respectively. While the physiological role of exocrine p- creas is to secrete digestive enzyme responsible for our normal digestion, absorption and assimilation of nutrients, the endocrine pancreas is to secrete islet peptide h- mones maintaining our glucose homeostasis. The pancreatic functions are nely regulated by neurocrine, endocrine, paracrine and/or intracrine mechanisms. Thus, dysregulation of these pathways should have signi cant impacts on our health and disease. Nevertheless, the underlying mechanisms by which pancreatic functions are regulated remain poorly understood. Recent basic science and clinical studies con rm myriad physiological and pathophysiological roles of the tissue renin-angiotensin systems (RAS). Of parti- lar interest is the recent identi cation of a local and functional RAS in the pancreas, which in uences both its exocrine and endocrine function. Its role in the pat- genesis of pancreatic diseases including diabetes and pancreatitis is increasingly recognized, as is the therapeutic potential of RAS antagonism: RAS blockade l- its disease progression of type 2 diabetes mellitus and impaired glucose tolerance, and may also protect against pancreatic in ammation.

Growth Hormone and the Heart endeavors to bring together knowledge that has been accumulated in the area of GH and the heart, from basic to clinical studies, by research groups working on this topic throughout the world. Lessons from different experimental models and from several human diseases (acromegaly, adult GH deficiency, heart failure) suggest to endocrinologists and cardiologists that GH may not only have a role in the physiology and pathophysiology of heart function, but that GH itself may have a place in the treatment of primary heart diseases (such as dilated cardiomyopathy) or of cardiac complications of hypopituitarism. Growth Hormone and the Heart will be a useful update of the research produced in the field of cardiovascular endocrinology. The Editors also hope that this book will serve as the primary step in the recognition of the wide physiological and clinical significance of GH and heart interactions.

It is an authentic privilege to have the opportunity to assemble and edit a new volume on "Prolactin," the first in several decades to be devoted to this fascinating hormone in all its aspects. The obvious clinical rationale for understanding prolactin (PRL) is the frequent occurrence of prolactinomas, the most common type of pituitary tumor. Fortunately, medical management of prolactinomas can be based on our under standing of the physiology of hypothalamic control of the lactotroph. Armed with this knowledge, therapies for proiactinomas are highly successful and well tolerated. Be cause of the historical and practical importance of knowledge regarding the hypothala mus-Iactotroph axis, the first chapters of this volume are dedicated to reviewing the physiology, development, and cell biology of lactotroph regulation. Chapters focusing on prolactinomas and related clinical issues follow these. PRL is the primary hormone that is responsible for "parental care" in many verte brate species. This reproductive strategy is not unique to mammals, but it has devel oped through evolution to be the central distinguishing feature of the mammalian life cycle. Among the mammals, mice have become the most effective research species in recent years. This can be traced to the development of a wide range of methods for manipulating mouse genetics, and thereby influencing development, physiology and behavior. Mice also provide a profound illustration of the physiological challenges faced in maternity. Female mice undergo a post-partum estrous, and often are both pregnant and lactating simultaneously.

The dramatic recent expansion in genomic information has motivated the development of new approaches to characterize gene expression and function. A critical issue for both basic and clinical endocrinologists is the physiological role of genes involved in regulating endocrine functions. Transgenic technologies allow the translation of genotypic information into specific phenotypes by using gene overexpression or loss of specific gene functions. Murine functional genomics is thus of central importance in modem biomedical endocrine research. Although mice are at present, the preferred mammalian species for genetic manipulations because of the availability of pluripotent embryonic. stem cells and inbred strains and the relatively low breeding and maintenance costs, transgenic rats have also been generated and used to study endocrine physiology. The two basic techniques used in the creation of transgenic animal models are integration of foreign DNA into a fertilized oocyte by random chromosomal insertion and homologous recombination in embryonic stem cells that are then introduced into zygotes. Transgenic mice and rats serve as sophisticted tools to probe protein function, as models of human disease, and as hosts for the testing of gene replacement and other therapies. Embryonic stem cell libraries for mouse gene deletion are being developed, which will make it possible to generate knockout mice rapidly and without the need to analyze gene structure, construct targeting vectors, and screen embryonic stem cell clones. A novel approach to transgenesis for the expression of DNA within adult differentiated neuroendocrine cells in vivo is using viral vectors.

The pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM) has attracted the interest of our group during the last three decades. As early as 1969, a Nobel Symposium dealing with this topic was organized in Stockholm. This was followed in 1987 by a Nobel Conference devoted to the same subject. The main purpose of these meetings was to bring together the most distinguished scientists from all over the world and present theories on molecular and genetic mechanisms responsible for the development of glucose intolerance in NIDDM. This idea was followed also in the present symposium, "New Concepts in the Pathogenesis of NIDDM," organized with diabetologists from Toronto in Canada. Our purpose is to biannually organize international meetings covering important aspects of dia betes research, hoping that this type of interaction may result in new concepts and treat ment alternatives. For us, participating in this symposium in September 1992, the meeting in Stockholm was very stimulating and innovative. It is a special pleasure that almost all invited lecturers submitted manuscripts. Thus, the publication of the proceedings of the symposium makes it possible for all interested in diabetes research to share new ideas and findings presented at the meeting. Claes-G6ran Ostenson Suad Efendic Mladen V ranic v CONTENTS REGULATION OF INSULIN SECRETION Impaired Glucose-Induced Insulin Secretion: Studies in Animal Models with Spontaneous NIDDM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. -G. Ostenson, A. Khan, and S. Efendic Perturbation ofIslet Metabolism and Insulin Release in NIDDM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 WJ. Malaisse 2 Regulation of Cytoplasmic Free Ca+ in Insulin-Secreting Cells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ."

This volume contains the edited proceedings of the Totts Gap Colloquium on Diabetes Mellitus, DILEMMAS IN DIABETES. The Collo- quium, lasting two and a half days, was organized mainly as a dia- logue among experts in the field with different disciplinary back- grounds and, to some extent, differing points of view. The effort was to synthesize existing knowledge, reconciling disparate data and interpretation, and pointing up important areas of ignorance. Thus, the book should serve not only as a summary of recent information on diabetes, but as a reliable guide to the practicing physician as he wades through often conflicting etiologic dogmas and therapeutic practices. The Colloquium was made possible through the generous support of the Geigy Pharmaceutical Company and the conscientious and expert coordination of Mr. Oscar Swarth. The participants were: Dr. George F. Cahill, Boston, Massachusetts Dr. Harvey C. Knowles, Cincinnati, Ohio Dr. Rachmiel Levine, Duarte, California Dr. Lelio Orci, Geneva, Switzerland Dr. Norton Spritz, New York, New York Dr. Roger Unger, Dallas, Texas Dr. Robert Williams, Seattle, Washington Dr. Stewart Wolf, Galveston, Texas Dr. Arnold Lazarow and Dr. I. Arthur Mirsky were to have partici- pated, but unfortunately were ill at the time of the meeting. Others in attendance included five medical students, especially selected from medical schools in the Philadelphia/New York area.

Dr. Robert L. Jackson, Professor of Child Health at the Uni versity of Missouri-Columbia, decided to retire from clinical practice in 1977 and the Department of Child Health planned a con ference in his honor. The Thirteenth Annual MidweSt Conference on Endocrinology and Metabolism also was in the planning stages and scheduled for two days in the fall. It seemed appropriate to com bine the two into an expanded three-day conference. In view of Dr. Jackson's international reputation in the study and care of children with diabetes mellitus, the conference topic was not dif ficult to find. Experts in this field were delighted to be asked to speak at a conference in Dr. Jackson's honor. We selected a number of excellent speakers to survey the physiology and pathophy siology of pancreatic hormones and their effects in diabetes mel litus, to discuss current knowledge of the microvascular complica tions of the disease, and to put it all into the proper historical perspective of where we have been and where we are going. We think the conference achieved its objective to pay meaningful trib ute to a distinguished member of the scientific community. As with any conference, the conversion of the presentations and discussions to the printed page is a long and arduous process. Many manuscripts were completed well after the conference and references often are more recent than the date of the conference."

Recent Developments in Graves' Ophthalmopathy offers an overview of the pathogenesis, assessment and management of patients with thyroid-associated eye disease. Each chapter is written by an expert and truly represents the current state of the art on the particular topic. This book can therefore almost be considered a textbook on this enigmatic disorder. Recent Developments in Graves' Ophthalmopathy is designed for all those interested in this disease, including basic scientists, clinical endocrinologists, ophthalmologists, radiotherapists, and orbital surgeons. The book gives a comprehensive overview of all aspects of Graves' ophthalmopathy. Subjects covered include the pathology of Graves' eye disease and the controversial views on its autoimmune pathogenesis; assessment of the eye changes using reliable measurements; medical management of Graves' eye disease with an overview of the many treatment options available to the clinician, including orbital radiotherapy and other immunosuppressive treatments; management of the thyroid disease; and finally, the techniques for performing various surgical procedures, which are explained and illustrated.

Since the late 1960s, there has been an acceleration of research focused on understanding how the efferent ducts, the epididymis, and the vas deferens function with respect to the maturation and storage of spermatozoa and as hormone dependent tissues. Another major interest in the epididymis is that it is an attractive target for the development of male contraceptives. There are well over 16,000 peer reviewed articles in the literature on these tissues, their structure, gene expression, protein synthesis and function. Regular international meetings have been initiated that are dedicated to this field. Thus, there is an urgent need for a comprehensive reference volume that spans every facet of epididymal biology, from historical background to the most current results, from basic cell and molecular biology to clinical issues. Well-established experts from every part of the world have contributed to this volume. By necessity, each author was given page limitations so that many topics are not dealt with exhaustively. Whenever possible, references to more comprehensive discussion of specific topics are included.

'Morphological imaging' and 'functional imaging' are current mainstays for the diagnosis, successful treatment and accurate follow-up of patients with endocrine disorders. Functional and Morphological Imaging of the Endocrine System provides the reader with comprehensive but concise insights in the application of cutting edge imaging techniques and updated imaging protocols for the diagnosis and treatment of hypersecretory hormonal syndromes and functional endocrine masses.

These Proceedinqs of the Midwest Conference on Endocrinology and Metabolism are being published by Plenum Press for the first time. Earlier Proceedings in the series Vlere published by the University of Missouri at Columbia. The shift to an internationally recognized pub lisher reflects the considerable growth in stature that the Midwest Con ferences have undergone since their inception nine years ago. Originally concerned only with the endocrinology of the thyroid, the Conferences now explore other endocrine areas. Efforts are made to assemble a panel of speakers selected from different sub-disciplines within endocrinology for the purpose of addressing a common problem. The Ninth Conference typifi es til i s approach. The format used in recent Conferences is not unique, but is unfor tunately encountered too rarely. A few prominent scholars are invited to come together to expound their findings and concepts in considerable depth, and to participate in a discussion which, together with the for mal presentation, is published in the Proceedings. The discussion, noted for its unhurried nature, permits wide participation by the audi ence. The subject of the Ninth Conference is one which is basic and im portant not only to endocrinology but also to biology in general. Many, possibly most, life processes change in a rhythmic fashion, with similar states recurring at regular time intervals. This rhythmic property of living systems expresses itself as a recognizable and definable pattern or "time-form" in a manner equivalent to the more customary spatial form."

After a decade or longer, approximately one-third of individuals with either type 1 or type 2 diabetes commence a downhill course in which decreasing renal function and failing vision define a Renal-Retinal Syndrome, dominating all aspects of life and presaging early death. Only a generation ago, survival after onset of end-stage renal disease (ESRD) in diabetes was limited because rehabilitation was preempted by blindness, limb amputation, stroke, and heart disease. By 1998, however, team management has improved the outlook, with preserved sight and return to work and home responsibilities, usually for a decade or longer, following kidney transplantation and laser photocoagulation. Recognition of the critical requirement for blood pressure regulation and metabolic control are central themes in management. In this unique book, the accomplishments of ophthalmologists, nephrologists, diabetologists, transplant surgeons, and basic scientists are blended into a strategic approach that may be readily applied by all those caring for diabetic patients. Each of twenty-one presentations suitable for primary care physicians, as well as for subspecialists concerned with macrovascular and microvascular complications of diabetes, is placed in perspective by an introductory editorial analysis. Promising near-term innovative therapies, including insertion of genetically engineered beta cells or polymer-coated islets of Langerhans, interdiction of kinins that promote retinal angiogenesis, and prevention of synthesis of advanced glycosylated endproducts (AGEs), are presented in detail. While comprehensive care of diabetic patients reflects multiple incremental advances that in sum afford major benefit, this text envisions further remarkable changes likely to suppress and possibly entirely prevent the Diabetic Renal-Retinal Syndrome.

Leading medical specialists critically review for the general practitioner the latest techniques for the clinical management of diabetic neuropathy. These authoritative contributors focus on the practical aspects of diabetic neuropathy and describe in detail the treatments that are currently available or expected to become available in the near future. They also include concise discussions of the causes of diabetic neuropathy and highlight the relatively unknown features of neuropathy that can significantly impact a patient's life. Comprehensive, up-to-date bibliographies at the end of each chapter provide an opportunity for the interested physician to gain a more detailed picture of a particular topic. This book offers family physicians, internists, endocrinologists, podiatrists, cardiologists, neurologists, and gastroenterologists an authoritative practical guide and a vital day-to-day reference source for the management of their neuropathic diabetic patients.

Fresh insights into the pathogenic mechanisms by which hyperglycemia induces tissue and organ injurt are the basis for rapidly evolving promising therapies in diabetes. Especially promising as targets for intervention are products of oxidative stress, including kinins and growth factors. Improving results of renal replacement regimes now incorporating pancreatic islet transplants are able to delay and prevent end-organ damage in diabetic individuals. The evolving story of the taming of diabetes is of direct concern to nephrologists, endocrinologists, ophthalmologists, primary care physicians and medical students.

This volume is a collection of the most significant contributions to the 4th International Symposium on MULTIPLE RISK FACTORS IN CARDIOVASCULAR DISEASE: STRATEGIES OF PREVENTION OF CORONARY HEART DISEASE, CARDIAC F AlLURE, AND STROKE held in Washington, D. C. in April 1997. The meeting focused on the risk factors for cardiovascular disease and their interactions. The need for this symposium is based on the epidemiological, clinical, and biological evidence that individuals from industrialized countries often possess two or more risk factors which synergistically increase the global risk profile. This has become more evident in recent years with the increase in life expectancy of populations in the industrialized countries. The evidence that a combination of risk factors confers a very high risk of developing cardiovascular diseases, is of pivotal interest in the process of detection of patients who will benefit the most from pharmacological treatment. Many recent epidemiological data identifying the intrinsic and environmental factors contributing to the development of atherosclerosis are discussed. These results, in parallel with basic and clinical research, underline atherosclerosis as a complex and multifactorial process involving the influences of lipids, including lipoprotein subfractions, blood pressure rheologic forces, carbohydrate tolerance, and thrombogenic factors, including fibrinogen, tissue factor, PAl-I, and homocysteine. Furthennore, the risk associated with anyone of these risk factors varies widely depending on the level of the associated atherogenic risk factors. Hyper cholesterolemia and hypertriglyceridemia, for instance, are more common than would be expected by chance among hypertensive patients.

Diabetes and cardiovascular disease together account for the largest portion of health care spending compared to all other diseases in Western society. This work seeks to provide an understanding of the causes of diabetes and its cardiovascular complications. As this understanding becomes more widely appreciated, it will serve as a foundation for evidence-based care and wider acceptance of sound science. The International Conference on Diabetes and Cardiovascular Disease, held in Winnipeg, in June 1999, was organized to bring together a multi-disciplinary group of researchers dedicated to further knowledge amongst researchers, care givers, and the managers of the health system. The invited speakers submitted their works for publication, which serves as the basis for this book. Major themes include: epidemiology of diabetes mellitus, metabolic risk factors in diabetes and cardiovascular disease, hypertension in diabetes mellitus, cardiac function in diabetes, glycemic control and improved cardiovascular function, diabetes management, and endothelial function in diabetes.

In a rapidly evolving and extremely important area of medical science, it is often difficult for the student, teacher, and researcher to keep abreast of all the important advances. The purpose of Molecular Biology ofDiabetes, Parts I and II is to bring to these individuals the latest knowledge of diabetes-related research in a comprehensive, yet concise manner. To this end, we have assembled chapters, written by most of the world's experts in the field, that we believe compre hensively survey and synthesize a coherent understanding of the subject. Studies of the etiology of type I and type II diabetes are extremely exciting and essential, since we hope to one day prevent the disease using gene therapy. These aspects are covered in Molecular Biology of Diabetes: I. Autoimmunity and Genetics; Insulin Synthesis and Secretion. In type II diabetes, an abnormality in pancreatic secretion exists concomitantly with peripheral insulin resistance. This abnor mality of insulin secretion is believed to be related to a defect(s) in glucose sensing. Uncoupling of glucose sensing from insulin secre tion may be the crucial step in the pathogenesis of noninsulin-depen dent diabetes. In this volume, we have invited authors to describe their studies on all known factors affecting ~-cell function, including autoimmunity and genetics of diabetes, as well as molecular mecha nisms of insulin synthesis and secretion. In the last few years, the most rapidly advancing area of research in diabetes has been, in fact, related to insulin action.

Brain Neurosecretory Cytokines: Immune Response and Neuronal Survival summarizes the biological and chemical data of signal molecules of the brain neuroendocrine immune system, mainly proline-rich peptides, which play an important role in the regulation of immune response, neuronal survival, hematopoiesis, and adaptation. The author also describes the role of PRPs for the protection of neurons against neurodegenerative disturbances and diseases. Brain Neurosecretory Cytokines: Immune Response and Neuronal Survival will be of great aid to the researchers and students in various areas of neurobiological profile (neurochemistry, neuroendocrinology, neurophysiology, and endocrinology).

Growth Hormone is a fitting addition to the Endocrine Updates Series. The aim of these publications is to provide the clinician with cutting-edge, yet succinct, access to the latest advances in endocrinology. Current interest in this rapidly evolving area of endocrinology makes this a timely and important update. Growth Hormone joins Dr. Fagin's Thyroid Cancer in continuing the standard of excellence as the fourth volume in this series of topical updates. Shlomo Melmed, MD, Series Editor, Endocrine Updates Ten years ago, many endocrinologists were still skeptical that growth hormone (GH) played an active role in adult metabolism. This is, perhaps, surprising given that GH deficiency (GHD) in adulthood had been `recognized' as long ago as the 1960s. During the last ten years studies have shown that GHD in adulthood is a far-reaching syndrome associated with abnormal body composition, reduced bone mineral density with an increased fracture rate, increased cardiovascular morbidity and impaired cardiac function, as well as reduced exercise performance and decreased psychological well-being. Importantly, it is also clear, from placebo-controlled trials, that GH replacement therapy can normalize body composition, increase bone mineral content and improve the cardiovascular risk factor profile. GH replacement therapy also improves cardiac performance and exercise capacity, increases muscle strength and improves well-being and quality of life. The aim of Growth Hormone is to provide a critical update of current knowledge about adult GHD and the future role of GH/IGF-1 in adult medicine. For this purpose, contributions from a number of research groups have been invited. It is my hope that the book may not only serve as an introduction to the field, but also stimulate further research within this exciting area.

The Seventh International Congress of Mucosal Immunology held in Prague, the beautiful old capital of The Czech Republic, 16-20 August 1992, was the first to be sponsored by the Society for Mucosal Immunology, and was the largest since their inception 20 years earlier in Birmingham, Alabama. It was attended by 624 participants who gave 538 presentations, more than 10 times the numbers of the first meeting; these proceedings contain 354 papers that were submitted for publication. The political events in Europe that made it possible to hold this Congress in Prague also allowed for the first time the participation of large numbers of scientists from Eastern Europe, as weil as from Asia, and the organizers were truly gratified by this happy circumstance. It is now clear not only that mucosal immunityencompasses the huge area of mucosal surfaces and most physiological organ systems, but also that mucosal immunology extends over the whole global surface and all continents! The sheer size of the Congress and number of manuscripts unfortunately entailed some unexpected problems in editing and assembling the proceedings, partly due to the diversity of linguistic styles not represented at earlier meetings, and we apologize to the authors who have patiently awaited the publication of their contributions.

Aaron I. Vinik, M.D., Ph.D. I IEastem Virginia Medical School The Diabetes Institutes Norfolk, Virginia 23510 This symposium, held in June 1991, was a gathering of international scientists to exchange their views on current concepts of cell growth and differentiation. Each scientist was asked to present a topic of their research related to cell growth and regeneration and to participate in a round table conference elaborating on current knowledge and sharing their experiences. By furthering this promising area of endeavor, a means of understanding ontogeny of cell development and of providing insights into tumor biology would prevail. Of prime importance was the anticipation that new information from a better understanding of the normal evolution of the pancreatic islet would generate alternative approaches to curing diabetes. This forward serves as a short introduction to the concept of pancreatic islet regeneration and the models currently in use to study the process. DEVELOPMENTAL ORIGIN OF ISLETS DURING EMRYOGENESIS The developing pancreas appears as a protrusion from the dorsal surface of the l embryonic gut. The different islet cell types appear sequentially during development in vivo. It therefore seems reasonable to propose that coordinated growth is dependent upon specificity of growth factors.