Preface

We have entered an era of outstanding achievements in the fields of molecular biology, genetics, and clinical embryology. The sequencing of the human genome has been achieved, and several mammalian species, as well as the human embryo, have been cloned. Scientists have created and isolated human embryonic stem cells, and suggestions for their use in treating certain intractable diseases continue to generate widespread debate. These remarkable scientific developments have already provided promising directions for research in human embryology, which will have an impact on medical practice in the future.

The 9th edition of The Developing Human (TDH) has been thoroughly revised to reflect our current understanding of some of the molecular events that guide development of the embryo. This book also contains more clinically oriented material than previous editions; these sections are highlighted in color to set them apart from the rest of the text. In addition to focusing on clinically relevant aspects of embryology, we have revised the clinically oriented problems with brief answers and added more case studies online that emphasize that embryology is an important part of modern medical practice.

This edition follows the official international list of embryological terms (Terminologia Embryonica, 2011). This list was developed by the Federative International Committee on Anatomical Terminology (FICAT) and was approved by the General Assembly of the Federative World Congress of Anatomy held in Cape Town, South Africa, in August 2009. The assembly represents the 60 Member Associations of the International Federation of Associations of Anatomists (IFFA). It is important that doctors and scientists throughout the world use the same name for each structure.

This edition includes numerous new color photographs of embryos (normal and abnormal). Many of the illustrations have been improved using three-dimensional renderings and more effective use of colors. There are also many new diagnostic images (ultrasound and MRI) of embryos and fetuses to illustrate their three-dimensional aspects. An innovative set of 16 animations that will help students to understand the complexities of embryological development now comes with this book. When one of the animations is especially relevent to a passage in the text, the icon has been added in the margin. Maximized animations are available to teachers for their lectures who have adopted TDH (consult your Elsevier representative).

The coverage of teratology has been increased because the study of abnormal development of embryos is helpful in understanding risk estimation, the causes of birth defects, and how malformations may be prevented. Recent advances in the molecular aspects of developmental biology have been highlighted (in italics) throughout the book, especially in those areas that appear promising for clinical medicine or have the potential for making a significant impact on the direction of future research.

We have continued our attempts to provide an easy-to-read account of human development before birth. Each chapter has been thoroughly revised to reflect new findings in research and their clinical significance. The chapters are organized to present a systematic and logical approach that explains how embryos develop. The first chapter introduces readers to the scope and importance of embryology, the historical background of the discipline, and the terms used to describe the stages of development. The next four chapters cover embryonic development, beginning with the formation of gametes and ending with the formation of basic organs and systems. The development of specific organs and systems is then described in a systematic manner, followed by chapters dealing with the highlights of the fetal period, the placenta and fetal membranes, and the causes of human birth defects. At the end of each chapter there are summaries of key features, which provide a convenient means of ongoing review. There are also references that contain both classic works and recent research publications.