The field of endocrinology is concerned with the hormonal mechanisms that regulate many bodily functions, including metabolism, growth, reproduction, electrolytes and water balance. In recent years, endocrinology has expanded to include a broader range of human experiences, such as aging and longevity, gender identity, and transplantation. These developments have been made possible by interdisciplinary research in endocrinology. Molecular modeling has led to the development of novel medications, and stem cell research has opened new avenues for treating previously incurable endocrine diseases, such as diabetes. However, these advances have also given rise to new ethical dilemmas that require interdisciplinary research to resolve. For example, medical ethicists, philosophers, and religious authorities are engaged in heated debates regarding the use of stem cells and the potential risks associated with dismantling the human embryo, which many consider to be the alteration of human life. This book addresses some of these challenges, caused by recent advances in the biology and medicine, and hopes to shed light on their impact in the field of endocrinology. This book is primarily intended for endocrinologists, but we hope it will also be useful to scientists and practitioners in other medical fields, and a guide for future medical practice and research. .