Essential Developmental Biology 3rd Edition

Book Preface

This book presents the basic concepts and facts relating to the developmental biology of animals. It is designed as a core text for undergraduate courses from the second to the fourth year, and also for first year graduate students. The first and second editions were “road tested” by myself and by many other instructors, and were found suitable for both biologically based and medically oriented courses. A basic knowledge of cell and molecular biology is assumed, but no prior knowledge of development, animal structure, or histology should be necessary.

The book is arranged in four sections and the order of topics is intended to represent a logical progression. The first section  introduces the basic concepts and techniques. The second covers the six main “model organisms,” Xenopus, zebrafish, chick, mouse, Drosophila, and Caenorhabditis elegans, describing their early development to the stage of the general body plan. The third deals with organ development, mostly of vertebrates but including also Drosophila imaginal discs. The fourth deals with some topics of high contemporary interest: growth and stem cells, regeneration, regenerative medicine, and evolution. To assist readers unfamiliar with the families of genes and molecules that are important in development, they are listed in the

Appendix in the context of a short revision guide to basic molecular and cell biology.

Like the previous editions, the new version of Essential Developmental Biology differs from its main competitors in four important respects, all of which I feel are essential for effective education.

• It keeps the model organisms separate when early development is discussed. This avoids the muddle that arises all too often when students think that knockouts can be made in Xenopus, or that bindin is essential for mammalian fertilization.
• It avoids considerations of history and experimental priority because students do not care who did something first if it all happened 20 years ago.
• It does, however, explain why we believe what we do. Understanding does not come from simply memorizing long lists of gene names, so I continue to explain how to investigate developmental phenomena and what sorts of evidence are needed to prove a particular type of result.

• The work is highly focused. In order to keep the text short and concise I have not wandered off into areas such as the development of plants or lower eukaryotes, that may be very interesting but are really separate branches of biology.

The first two editions were very well received by both users and reviewers and I hope that the third edition will make this book an even more popular choice for undergraduate and graduate level teaching around the world.

The curse of detail

The principal challenge today is that of exponentially increasing detail. The molecular life sciences seem to double in workforce and output every 10 years or so, and developmental biology has grown at least this fast since its re-founding as a molecular subject in the 1980s. But students’ brains do not double in size every 10 years, nor do their courses lengthen. So very serious thought has to be given to what to include and what to leave out.

I have taken the view that the value of model organisms is that they enable experiments to be performed whose results illuminate some general principle of development. However, a lot of recent research has diverged from this strategy and has focused on an ever more detailed molecular analysis of every possible process and organ system in every model organisms. Although the principles of development are common to all animals, it is inevitable that the harder you look, the more differences between organisms you will find. My view is that for a textbook at this level it is not appropriate to cover all the detailed differences between, say, myogenesis in mouse, chicken, Xenopus, and zebrafish, so I have focused on just the main themes. In the general field of organogenesis it is also not feasible to cover all of the organs in the vertebrate body. Accordingly, I have selected for inclusion those that are classic developmental biology topics, such as limb development, and those of the greatest medical importance, such as the nervous system, the heart, or the pancreas. Likewise, when considering regeneration, it is not possible to cover every structure in the living world that regenerates to some extent, so I have focused on three classic systems: the planarian, insect limbs, and vertebrate limbs.