The epididymis has great significance in the reproductive biology of the male and it is gaining recognition as an organ worthy of study in its own right - where the secretory and absorptive activities of one tissue (the epithelium) profoundly modify the function of another (the spermatozoon). Apart from cases of epididymal agenesis or physical blockage, however, it is not yet known to what extent mal functions of the epididymis contribute to "unexplained" male infer tility, but its importance as a target for antifertility agents in the male is now widely appreciated. This monograph evolved from two lectures on epididymal func tion given at the National Research Institute for Family Planning, Beijing and the Sichuan Provincial Family Planning Research Insti tute, Chengdu, China in 1983. In order to stress for this audience the central importance of the epididymis in fertilisation, and so highlight its potential for attack by antifertility agents, the talks attempted to put the epididymis in reproductive perspective by stressing the func tional development of the sperm cells during their sojourn in the epididymis, rather than merely listing the changes observed in them."

The present monograph will concern itself with those disorders of the endocrine system, either associated with destruction, interference with function or hyper- function, which are considered to be due to auto-immune processes. Endocrinopathies Non-endocrine auto-immune disorders associated with the endocrinopathies Graves' (Basedow's, Parry's) disease Pernicious anaemia Hashimoto's thyroiditis Vitiligo Idiopathic Addison's disease Myaesthenia gravis Insulinopenic diabetes mellitus Sjogren's syndrome Auto-immune oophoritis and orchitis Rheumatoid arthritis Auto-immune hypoparathyroidism Idiopathic thrombocytopenic purpura Auto-immune hypophysitis Chronic active hepatitis Possibly some cases of infertility Primary biliary cirrhosis due to anti-sperm antibodies Reproduced with permission from Volpe (1977) The above table indicates those organ-specific endocrinopathies considered to be due to auto-immune factors, as well as those non-endocrine, organ-specific auto-immune disorders which may be associated with them (Volpe 1977). It is evident that such disorders, occurring without any obvious external cause, raise the very elementary question of how immune processes directed against self- constituents could be initiated. Generally, of course, the immune system acts as a regulatory and defence mechanism, and disorders of auto-immunity represent breakdowns in this regulatory system. The following chapters will be concerned with the individual components ofthe endocrine system so affected by auto-immune processes; it will first be necessary to provide an initial chapter for the purpose of summarizing some general principles of immunology, in order to place the immune disorders of the endocrine system in context.

Research on the hormonal control oflactation - the subject of this monograph - has long been the major interest of this laboratory. Studies were initiated in the mid 1930s by the late Professor S. 1. Folley, FRS, who directed the work with immense enthusiasm and devotion until his untimely death in 1970. This fruitful area of basic and applied research has, in recent years, attracted widespread attention; there have been many exciting events and developments with a dramatic increase in the number of publications. These events are diverse and include the identification, isolation and sequencing of human prolactin; the identification and isolation of placentallactogens in several ruminant species with recognition of their importance in mammary growth and differentiation; the introduction of highly sensitive bioassay, radioimmuno- and radioreceptor-assay techniques for mammotrophic hormones; the growing clinical appreciation of the immunological and nutritional importance of colostrum and milk to the newborn; the intensification of studies on normal mammogenesis to establish a sound basis for studies on mammary cancer; and the exploitation of the mammary gland, with its characteristic differentiation patterns and multiple synthetic abilities, as a valuable tissue for the investigation of basic mechanisms involved in the synthesis under hormonal control of enzymes and secretory proteins; and for the study of hormone - receptor interactions.

The European School of Oncology came into existence to respond to a need for informa tion, education and training in the field of the diagnosis and treatment of cancer. There are two main reasons why such an initiative was. considered necessary. Firstly, the teaching of oncology requires a rigorously multidisciplinary approach which is difficult for the Univer sities to put into practice since their system is mainly disciplinary orientated. Secondly, the rate of technological development that impinges on the diagnosis and treatment of cancer has been so rapid that it is not an easy task for medical faculties to adapt their curricula flexibly. With its residential courses for organ pathologies and the seminars on new techniques (laser, monoclonal antibodies, imaging techniques etc.) or on the principal therapeutic controversies (conservative or mutilating surgery, primary or adjuvant chemotherapy, radiotherapy alone or integrated), it is the ambition of the European School of Oncology to fill a cultural and scientific gap and, thereby, create a bridge between the University and Industry and between these two and daily medical practice. One of the more recent initiatives of ESO has been the institution of permanent study groups, also called task forces, where a limited number of leading experts are invited to meet once a year with the aim of defining the state of the art and possibly reaching a consensus on future developments in specific fields of oncology.

Progress in basic research has made it necessary to redetermine the possibility of classic endocrine therapy for the treatment of patients with breast cancer. Exemplary, close cooperation between biochemis try and animal and clinical research led to a truly interdisciplinary and international exchange of ideas and experience at a symposium held in autumn 1978 in Heidelberg. We owe our thanks to ICI-Pharma for the kind support of this sym posIUm. The participation of Charles Huggins in the meeting as honorary chairman signified to all participants the meaning of this joint endeavour. It was the same Charles Huggins who through experimental work laid the foundation stone for endocrine ther apy of prostate and breast cancer, and who applied his findings clinically. Thousands of patients owe to him relief from their suffering. He contributed greatly to the attempt to find and stabilize the endocrine therapy for breast cancer, for which we thank him sincerely. We hope that the following contributions will similarly serve the well-being of our patients."

It is well established that progesterone plays a role in the brain and hypophysis as a facilitator and inhibitor of sexual behavior and gonadotropin release in the female rat (Everett 1961; Caligaris et al. 1971; Brown-Grant and Naftolin 1972; Dorner 1972; Meyerson 1972; Barraclough 1973; Goldman and Zarrow 1973; Mann and Barraclough 1973; Freeman et al. 1976; Feder and Marrone 1977; Goodman 1978; Attardi 1981), guinea pig (Morin and Feder 1974), and primates (Odell and Swerdloff 1968; Spies and Niswender 1972; Yamaji et al. 1972; Karsch et al. 1973; Dierschke et al. 1973; Knobi11974; Clifton et al. 1975). In an attempt to learn whether a specific progesterone uptake mechanism exists in the brain and the hypophysis, the distribution and retention pattern of radioactivity after in vivo injection of labeled progesterone was studied. Early work of Kato (1963) did not show a selective uptake of radioactivity in the hypo- thalamus of immature and estrogen-primed immature rats after injection oflow- specific-activity [14C]progesterone, but some tendency of the reticular formation to take up radiation was observed. Laumas and Farooq (1966) reported that after intravenous administration of labeled progesterone to ovariectomized estrogen- treated rats, radioactivity in the brain and pituitary appeared to show a very slight, insignificant increase 1-2 min after injection, but the uptake pattern was not definite, as had been seen with estradiol. Seiki et al.

Can the art of predictive medicine anticipate the development of diabetes? And if so, what can be done about it? How early is early enough to intervene effectively? With what therapeutic modality? Why? Big babies are not an infrequent occurrence in mothers with normal carbohydrate metabolism for another 10, 20, or even 30 years. The abnor- mality present during pregnancy is now accepted as what is inherited with the diabetic predisposition, or what can be recognized as the diabetic susceptibility. It occurs before hyperglycemia, during the phase of dy- namic resistance to diabetes, during the prediabetic period. Prediabetes means before diabetes, and was applied for the first time by Mara~on in Spain, to signify the stage before hyperglycemia. Foglia in Argentina used the term in 1944 for his pancreatectomized rats. We pub- lished the first paper on humans in 1951 (Camerini-Davalos, R.A., Landabure, P., and Serantes, N., Rev Med Cordoba 39: 187).

Following a low-carb, high-fat ketogenic diet helps you lose weight, feel great and enjoy better energy and mental clarity. More and more people are turning to this healthy and delicious way of eating, but with lots of information about macronutrients and ketosis, it can be hard to know where to begin. Keto Kitchen makes it easy, with simple, delicious and inspiring recipes that fit into your busy lifestyle. This fantastic collection of recipes has been created by talented chef and keto devotee Monya Kilian Palmer. From Brown-Butter Scrambled Eggs to Slow-cooked Lamb Shoulder with Roast Cherry Tomatoes, every recipe is packed with flavour and nutrients. There are even desserts, including a Dark Chocolate and Raspberry Tart and Lime Cheesecake. The dishes are rich, indulgent and tasty. This is not diet food as you know it. Monya Kilian Palmer is a chef and culinary consultant originally from Cape Town, South Africa. Since moving to the UK in 2012, she has worked for both Heston Blumenthal's Fat Duck Group and Le Cordon Bleu. She has been following the ketogenic lifestyle since mid-2018.

A variety of new techniques that promise to revolutionize the clinical management of early pregnancy are fully detailed in this state-of-the-art book. Leading international researchers describe fast-moving topics such as embryo manipulation and the diagnosis of congenital abnormalities. The technology of assisted reproduction has made it possible to study living embryonic material for the first time, which has led to rapid advances in our understanding of the human embryo's early development. For example, study of the embryo in the test tube has pointed to early pregnancy loss as a possible cause of later infertility. Even more important, diagnostic tests using sophisticated techniques of molecular biology can be run on single cells before the embryo is replaced in the uterus. Another area of advance is the diagnosis of congenital abnormalities in the first and second trimesters of pregnancy. Great improvements have been made in the techniques of chorion villus biopsy and ultrasound imaging. A spectrum of simple biochemical tests performed on the mother's blood can greatly improve the detection of Down syndrome and other chromosome defects. Together with other developments in the fields of molecular biology and endocrinology, these new diagnostic techniques are the beginning of a new age in clinical human genetics and embryology.

Publication of this monograph acknowledges great strides made in research on the zona pellucida during the past decade or so. The body of work presented testifies to a resurgence of interest in the zona pellucida, prompted largely by a renewed appreciation of its unique properties and its important functions during early mam malian development. It is gratifying to realize that the zona pellucida has at last achieved a well-deserved attention. Whereas extracellular coats of nonmammalian eggs have been studied intensively for many years, the zona pellucida by comparison, has until now taken a back seat. Fortunately, the research presented here signals an end to this situ ation. Many of the difficulties inherent in working with relatively small amounts of material have been overcome, paving the way for application of a wider variety of experimental approaches to the zona pellucida by a larger community of investigators. Hopefully, this monograph will serve as a catalyst in this regard. As revealed in these pages, application of contemporary experi mental methodologies has had significant impact on both pure and applied research on the zona pellucida. For example, modem im munological approaches have been used to assess molecular fea tures of zona pellucida structure and function, as well as to evalu ate the zona pellucida as a potential contraceptive target antigen."

In 1980 a case of myxedema was treated in Lisbon by the implantation of a sheep thyroid gland with the immediate improvement in the patient s condition. A few years later, medications for the then ill-explained condition of the menopause included tablets made from cow ovaries. In the first quarter of the 20th century the identification vitamin D3 and its sunlight driven production in skin paved the way to the elimination of rickets as a major medical problem. Twenty years or so later Sir Vincent Wigglesworth established the endocrine basis of developmental moulting in insects, arguably the most commonly performed animal behaviour on Planet Earth. A paradigm that would unify these disparate observations arose between in 1985 and 1987 beginning with the identification of the glucocorticoid receptor and the nuclear receptor super-family. What follows is a timely and positive manifestation of the capacity, productivity and value of international human scientific endeavour. Based on intrigue, lively competition and cooperation a global effort has rapidly fostered a school of biology with widespread ramifications for the understanding of metazoan animals, the human condition and the state of the planet. This book is the first this century to try and capture the spirit of this endeavour, to depict where the field is now and to identify some of the challenges and opportunities for the future. "

In the last decade, it has become increasingly evident that the clini- cal and morphologic changes underlying many of the complications of diabetes, including cataract formation, retinopathy, nephropathy, neuropathy, and macrovascular disease, are preceded by a variety of disturbances of biochemical and physiologic origin. Dr. Cohen has recently written a superb monograph, entitled Diabetes and Protein Glycosylation: Measurement and Biologic Relevance, in which she thoroughly explores how enhanced nonenzymatic glycosylation in uncontrolled diabetes underscores the pressing need for main- tenance of long-term euglycemia. In the present volume, The Polyol Paradigm and Complications of Diabetes, she reviews, in a most succinct and thorough manner, how another biochemical mechan- ism, involving the polyol pathway, is involved in the pathogenesis of such diabetes complications as retinopathy, neuropathy, nephropa- thy, and cataract formation. Dr. Cohen gives us a clearly written and comprehensive mono- graph, reviewing the chemistry of the polyol pathway and of the aldose reductase inhibitors, and the pathophysiologic significance of increased polyol pathway activity in a variety of tissues affected by Vlll Foreword diabetes mellitus. She insightfully describes the relationship of increased polyol pathway activity to altered metabolism of inositol- containing phospholipids and to changes in various tissue concentra- tions of myo-inositol. Finally, she provides us with a careful review of the existing experimental and clinical studies with a variety of different aldose reductase inhibitors that have been and are being performed in the hope of preventing or reversing long-term compli- cations of diabetes.

These four volumes comprlslng "GnRH Analogues in Cancer and Human Reproduction" are a distillation of the presentations of the invited speakers at a landmark International Symposium bearing the same name, organized by one of us (B. L. ) and held in Geneva, Switzerland in February 19B8. The Symposium was truly interdisciplinary spanning gonadal hormone dependent disease including various forms of cancer and ranging to control of fertility, both pro- and conception. The international flavor can be caught from the 480 participants and 259 contributors drawn from 14 countries. The Symposium, and therefore this book, would not have been possible without the backing of The International Committee for Research in Reproduction and the sponsorship of the International Society of Gynecologic Endocrinology, The Swiss Society of Fertility and Sterility, The University of Geneva School of Medicine, The Swiss Society of Endocrinology and The US Foundation for Studies in Reproduction Inc., and help from the World Health Organization. B. H. Vickery B. Lunenfeld June 1989 xiii LIST OF CONTRIBUTORS TO THE SERIES A. Abbondante H. Bartermann First Institute of Obstetrics and Urologische Universitatsklinik Kiel Gynecology Arnold-Heller Strasse 7 University "La Sapienza" 0-2300 Kiel 1, FRG Rome, ltaly M. Bartholomew P. Abel Department of Medicine/Endocrinology Department of Urology Milton S. Hershey Medical Center Pennsylvania State University Hammersmith Hospital DuCane Road PO Box 850, Hershey, PA 17033, USA London W12 OHS, UK D. Beck H.

These four volumes comprising "GnRH Analogues in Cancer and Human Reproduction" are a distillation of the presentations of the invited speakers at a landmark International Symposium bearing the same name, organized by one of us (B. L. ) and held in Geneva, Switzerland in February 1988. The Symposium was truly interdisciplinary spanning gonadal hormone dependent disease including various forms of cancer and ranging to control of fertility, both pro- and conception. The international flavor can be caught from the 480 participants and 259 contributors drawn from 14 countries. The Symposium, and therefore this book, would not have been possible without the backing of The International Committee for Research in Reproduction and the sponsorship of the International Society of Gynecologic Endocrinology, The Swiss Society of Fertility and Sterility, The University of Geneva School of Medicine, The Swiss Society of Endocrinology and The US Foundation for Studies in Reproduction Inc., and help from the World Health Organization. B. H. Vickery B. Lunenfeld June 1989 LIST OF CONTRIBUTORS TO THE SERIES H. Bartermann A. Abbondante First Institute of Obstetrics and Urologische Universitatsklinik Kiel Gynecology Arnold-Heller Strasse 7 University "La Sapienza" D-2300 Kiel 1, FRG Rome, ltaly M. Bartholomew P. Abel Department of Medicine/Endocrinology Department of Urology Milton S. Hershey Medical Center Hammersmith Hospital Pennsylvania State University DuCane Road PO Box 850, Hershey, PA 17033, USA London W12 OHS, UK D. Beck H.

This book is an edited collection of the literature on leptin beginning with the discovery of leptin and a study of its affect on animals and in humans. Chapters will focus on the discovery, history, roles and regulation of leptin in all the major areas of physiology, as well as on assay methods, phylogeny and genetics. The timing of this volume is long overdue and is the first comprehensive coverage of leptin physiology in the field.

- This series is indexed in index Medicus

- The turn around time for this series is fast, making the research as accurate as a journal

Biomedical devices that contact with blood or tissue represent a wide range of products. Depending on their potential harm to a body, medical devices are categorized according to the degree, so their safety can be assured. All biomaterials are by definition designed to contact with a body for a certain period of time. The nature of the body contact, as well as the duration a material contacts with the body may initiate unwanted biological In comparison with invasive devices Oike catheters and medical responses. implants contact directly with tissue or with the circulating blood) non invasive devices (like wound-dressings and contact lenses contact with the skin, the sclera, and the mucosa or with open wounds) have a lesser risk of hurting a patient. When blood contacts with a foreign material, plasma proteins become absorpted to the surface within a few seconds. The reactions that follow, the so-called intrinsic pathway lead to the formation of fibrin and activation of platelets and white blood cells, result in blood clot formation."

A little over 12 years ago I wrote a small volume entitled Infertility. It seemed to me at that time that significant advances in the field called for the publication of such a volume. The following is from the preface to that volume: During the past 15 years considerable progress has been made in the field of infertility diagnosis and management. It is perhaps a paradox that much of this increased knowledge has come about because of Western medicine's preoccupation with the search for a means to control reproduction. As a result, we have achieved new insights into the physiologic mechanisms involved in reproduction, and we have found better methods for measuring physiologic changes in reproductive health and disease. To these advances can be added improvements in the utilization of endoscopic and surgical techniques, in the diagnosis and treatment of infections and endometriosis, and in the treatment of hormonal disorders. During this period, too, through workshops and conferences and in journals and texts, these latest advances have been made available to physi cians, an outstanding example being the two volumes of Progress in Infer tility, edited by Drs. Jan Behrman and Robert Kistner. As necessary as these publications are, they do not offer an overall view of infertility diag nosis and management."

In the middle of the 17th century, the great French philosopher Rene Descartes wrote (L'Homme, J. Le Gras, Paris, 1669) that a suitable stimulation of the brain results in two types of "movements": exterior movements, designed to seek desirable ends and to avoid undesirable or harmful ones and interior movements or "passions" which through the release of "animal spirits" regulate the heart, the liver, and other organs. When it appears appropriate to meet a threat with force, the passion of rage causes the release of strong spirits, whereas when avoidance appears to be the better choice, the passion of fear causes the brain to release weak spirits. We do not know what influence, if any, Descartes had on the thinking of Walter B. Cannon (Bodily Changes in Pain, Hunger, Fear and Rage, Appleton and Co. , New York, 1920), of Hans Selye (The Story of the Adaptation Syndrome, Acta, Inc. , Montreal, 1952), ofG. W. Harris or of R. Guillemin (Hypothalamic-Hypophysial Interrelationships. A Sym posium. c. c. Thomas, Springfield, 1956), but it is interesting to reflect upon the durable value of great ideas which constantly resurface even if modified by other ideas and by new techniques, as if propelled by a preordained intellectual imperative.

THE STATE oF HoRMONE AcTioN levels were induced in concert with ligand occupa tion of certain membrane receptors and this second AND MoLECULAR REGULATION messenger (cAMP) was postulated to initiate intra cellular phosphorylation of unknown targets. At Molecular Endocrinology and Regulation is a this point, the field ofPeptide Hormone Action also burgeoning field, having experienced a remarkable came into being. period of growth since the late 1960s. At that time, These fields developed together for much ofthe there was no field of Hormone Action. The prevail next decade. Hormone Action Conferences invari ing view of how hormones worked ranged from ably contained talks on both types of receptors and effects on membrane transport of nutrients and progress was rapid and in concert with the explo precursors for RNA and protein synthesis, to effects sion molecular biology. In the steroid field, on the translation of mRN A at the level of ribo progress was more rapid initially, but by the mid somes. Therewas, however, asmallcadreofvoices 1980s, the peptide field attained equal mechanistic that predicted a possible nuclear action on mRN A status and the source of specialized conferences of synthesis. The first such paper was presented at the national endocrine meetings in 1967 and dealt with its own. Steroid hormone action investigators concen hormonal stimulation of oviductal protein synthe tratedonfirst understanding the "pathway" of action sis. It was about this time that a small group of for their hormones."

Is the nephrology community facilitating excess cardiovascular deaths in patients with kidney failure and anemia by treating to a subnormal hematocrit? Why have clinicians and nephrologists permitted health insurance companies and the government to decide when anemia therapy should begin in persons with progressive kidney failure? Is iron the only variable that can be manipulated to maximize response to recombinant erythropoietin? Are we using too much intravenous iron in kidney failure patients, and is oral iron supplementation worthless in sustaining iron stores during long-term erythropoietin treatment? When does left ventricular hypertrophy begin to emerge in patients with progressive renal disease and is there convincing evidence that anemia is a significant cause of LVH in this setting? Is darbepoetin alfa, a new novel, long-acting erythropoietin, really superior to recombinant erythropoietin? This book is a compilation of proceedings from a conference in Brooklyn convened to address these and other controversial and unresolved issues in renal anemia management.

The Third Advanced Seminar in Neurosurgical Research was held in the Palazzo Pisani Moretta, Venice, Italy from 30th April to 1st May, 1987 and was devoted to "Neuroendocrinological Aspects of Neurosurgery." The general aim of these advanced seminars is to bring together European Neurosurgeons interested or involved in research work, either clinically, experimentally or both, in a given field in order to achieve in-depth informal discussions not possible in the more conventional large congress. In particular, these advanced seminars seek to provide high level teaching by experienced basic scientists, to provide "state of the art" assessment of the subject and to highlight areas of controversy that may be suitable for future research. A special effort is made to identify younger neurosurgeons through the auspices of the European Directory of Neurosurgical Research, who have a particular interest in the subject under discussion, not all of whom will have immediate access to the most advanced, modern technology. The topic of Neuroendocrinology was chosen because clinically it is an area of controversy that should be amenable to application of new techniques, including molecular biology. There is a tendency on the part of Endocrinologists not to appreciate always that disturbances seen by Neurosurgeons may be different and need special attention. Inevitably there has been a little delay in publication of the manuscripts but these have been updated appropriately.

The elucidation of the structure, function, and clinical significance of the neurohypophysis has been one of the most rewarding chapters in the history of endocrinology. Diabetes insipidus, which can be manifested by passage of 15 liters of urine a day, is one of the most dramatic disorders of the endocrine system, and can readily be managed by replacement therapy with the natural secretions of this gland, or with synthetic analogues that provide a more favorable therapeutic ratio. The neurohypophysis is the archetypical neurosecretory gland. Its secretions arise within well defined nerve cells in the hypothalamus, are transported by axoplasmic flow to nerve endings in the neural lobe, are released in response to propagated action potentials, and are regulated by neurotransmitters and osmotic signals. This gland is a model for homeostatic regulation; functional disorders of this regulation lead to well defined disorders such as the syndrome of inappropriate secretion of antidi uretic hormone (SIADH), which can be mimicked by the ectopic secretion of its hormones by tumor cells. These hormones were the first peptides to be sequenced and synthesized chemically and their structure-function relations have been characterized as well as those of any of the peptide hormones. The concept that peptide hormones generally arise as products of the processing of a larger prohormone precursor was first developed from studies of the neurohypophysis. The concept of stimulus-secretion coupling was first ap plied in neuronal tissue to the neurohypophysis.

Every year there are new and exciting developments in assisted human reproduction, but how much do we really know about the underlying causes of infertility? This volume explores recent progress in the understanding of the genetics of spermatogenesis and male infertility. Topics include fundamental advances and current problems in the development and function of the testis, an outline of clinical findings in male infertility and an overview of the role of the Y chromosome in male fertility. Comprehensive critiques of posttranscriptional control during spermatogenesis, mammalian meiotic sterility, and comparative genetics of human spermatogenesis from the perspective of yeast, Drosophila and mice provide a global overview of the field.

This book brings together some of the results and ideas produced by a large number of people-colleagues and students with whom I am privileged to work in the laboratory at Rockefeller University. In terms of my personal history I see it as a confluence of creative forces persons from whom I have learned. I was instructed in neuroanatomy by Walle J. H. Nauta at M. I. T., and later in a course at Harvard Medical School under the direction of Richard Sidman. At Harvard Medical School, where M. I. T. graduate students were allowed to cross register, the superb neurophysiology course was under the guiding spirit of Stephen Kuffler. Later, I benefited greatly from participating in his summer course in electrophysiological techniques at Woods Hole. Eric Kandel and his colleagues have provided us with the most exciting contemporary approach to the conceptualization and study of cellular mechanisms for behavior. Here at Rockefeller, Carl Pfaffmann and Neal Miller have been leaders in every sense of the word. Not only did they provide me with opportunities to grow to scientific maturity; they also set an example of clear thinking about mechanisms for mammalian behavior patterns. I wrote this book to show how the systematic use of increasingly detailed electrophysiological, neuroanatomical, and neuroendocrine tech niques can explain the mechanism for a mammalian behavioral response. The behavior in question happens to be sensitive to steroid hormones and plays a central role in reproduction."