Elements of developmental biology

Developmental biology has differentiated into a rich, complex field that continues to progress at breathtaking speed. This presents a conundrum for textbook authors: present students with a comprehensive survey of the entire field or distill it down to the essence that provides students with a framework on which to hang the details and complexities. Fred H. Wilt and Sarah C. Hake have chosen the latter approach. Their target audience is students with a basic background in organismal, molecular and cellular biology who do not intend to make developmental biology their careers.

Is there a need for such a book? How well does it work? Does the book tell a compelling story that is as dynamic as the field itself? Would it be capable of corrupting students who never considered a career in development, tempting them to join the `dark side'?

The writing style is very accessible, verging on the vernacular, as opposed to a more scholarly style that is standard in most textbooks. Considering the intended audience, the style works quite well. In fact, it is fun to read. Consider this example from Chapter 3, which distills development down to its essence: `The general “recipe” for animal development was set forth in Chapter 1: make an egg, cut it up into many diploid cells, move cell groups from place to place to produce a three layered embryo, and selectively activate gene expression in different forming tissues and organs'. The rest of the book builds upon this simple statement. The authors have elected to feature a limited number of model organisms, rather than taking a more comprehensive approach that would use the full palette of organisms that developmental biologists study. The marginalization of C. elegans and the zebrafish is unfortunate, but choices were necessary to keep the book reasonably short. All chapters begin with a Chapter Preview, which gives readers the context and alerts them to the major concepts to be covered, and end with a summary of Key Concepts, Study Questions and Selected References. Suggested answers to the Study Questions can be found at the end of the book. This provides the book with an interactive aspect, assuming that students take advantage of the opportunity. An additional interactive tool will be the website, which is mentioned on the back cover of the book, but which was not yet `live' when I prepared this review.

The book begins by presenting the basic conundrum of development: how can a single cell, the fertilized egg, give rise to a complex and ordered assemblage of distinct cell types that function together in the adult, which produces another generation of gametes that contribute to yet another embryonic generation. The authors then outline the concept of differential gene expression, using classical examples and introducing experimental approaches that have been used to study this process. The second chapter is a brief introduction to gametogenesis and fertilization, with an even more succinct overview of cleavage as an introduction to fate mapping through lineage tracing. Given the intended readership, I am surprised that the authors did not take advantage of the opportunity to discuss reproductive biology in more detail. I cannot imagine a topic of more interest to university students! Next comes a series of overviews of oogenesis and early development in Drosophila, frogs, birds and mammals. In each case, the unique role that the organism has played in revealing developmental mechanisms is described, as well as the distinctive developmental processes employed by each group of organisms. In the mammalian section, the emphasis is on the mouse,which is the most extensively studied mammalian embryo. However, I think another opportunity was missed to `grab' students' interest by featuring human development more prominently.

The next section of the book features vertebrate organogenesis, culminating in metamorphosis. They precede the discussion of amphibian metamorphosis with a discussion of insect metamorphosis. I suspect that students will find this placement a bit confusing. The animal organogenesis section is followed by a section on plant development. It is up to the marketplace to confirm that there are sufficient non-specialist development courses that include plant development to justify its inclusion in the book. I hope that this is the case, because plant development is fascinating and highly relevant.

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The remainder of the book is devoted to revisiting topics that are been introduced in earlier chapters and discussing them in depth from a cellular and molecular perspective. Some plant topics are interspersed among mostly animal topics. The first two of these chapters deals with the cellular basis of morphogenesis: how do cells organize themselves into a complex, functional organism? Once again, the authors have missed an opportunity here. In this case, the discussion of cell motility is not complemented by a discussion of metastasis. I think it is instructive to relate academic topics to topics that are relevant to our daily lives – particularly in a book targeted to non-specialists. The final section of the book deals with the regulation of gene expression, returning to the conundrum presented at the outset: how do cells with identical genomes become so very different from one another during development? The book culminates in a fascinating chapter on `evo-devo'.

In summary, this is a noble effort that is well written. There is a need for a slimmed-down overview of development that is accessible to students who do not intend to specialize in the field. However, I would have preferred a book that did more to emphasize the relevance of developmental biology to them. Reproductive biology, cancer, tissue engineering, and reproductive and therapeutic cloning are topics that fascinate us all. We owe it to our students to inform them about them. It is easier to do that if their course textbook provides a foundation for the understanding of such topics.