scattered throughout his red bone marrow but not elsewhere. There were only the vaguest explanations for the precision of this distribution. What subtle interplay ...
L’A R T D E L A P R AT I Q U E V É T É R I N A I R E P R I V É E
la communication; il s’agit d’un défi qu’ils doivent relever ensemble. Ils conviennent tous qu’il est inacceptable que les membres du personnel offrent de l’information aux clients autre que celle contenue dans le feuillet sur ce sujet. À cette fin, ils rencontrent le personnel pour expliquer le feuillet et leur demander doucement mais fermement de diriger toutes les questions à ce sujet à l’un des vétérinaires en insistant sur le fait que cela n’est pas négociable en raison du tort que pourraient causer
des renseignements inexacts. Même si certains membres du personnel croient que leurs opinions personnelles sur ce sujet sont tout aussi valides, ils pourront accepter cette directive s’ils savent que les vétérinaires sont d’accord avec cette position et veulent seulement offrir un service de la plus grande qualité à leurs patients et clients. Même s’il n’y a personne pour offrir une médaille d’or au Dr DiSilva lorsqu’il quitte la clinique ce soir-là, il est confiant de l’avoir méritée. ■
Book Review Compte rendu de livre Veterinary Embryology McGready TA, Quinn PJ, FitzPatrick ES, Ryan MT. Blackwell Publishing, Ames Iowa, USA, 2006. 377 pp. ISBN 1-4051-1147-X. $103.95.
I
was concerned recently when a senior administrator of a veterinary college said to me, “We try to avoid teaching the students anything they don’t really need to know.” This simple sentence paints knowledge as a burden, calls into question the whole meaning of the words “university” and “profession,” and presupposes a gift of foresight denied to most of us. There is a fine balance, I believe, between the flexible but finite capacity of the student’s imagination and the obvious fact that knowledge is unbounded. The authors of Veterinary Embryology understand this. The authors, therefore, include all the fundamentals expected of an embryology text for veterinary students: early development, placentation, organogenesis, and common developmental anomalies. But in addition, the authors are not afraid to describe gastrulation in Amphioxus and amphibians; not, of course, for the benefit of frog breeding clients but to give scientific and historical context. And while cognizant of the past, the authors boldly reach to the future with discussions of the molecular fundamentals of cell signaling and the homologous behavior of Hox genes in the segmentation of both mammals and Drosophila. But then how could anyone resist talking about a gene called sonic hedgehog, or a protein called “frizzled activating” another called “deshevelled.” The writing is generally sound. I was, for example, entirely clueless about a technique called RNA interference but a short paragraph later I knew enough for the moment. There are plenty of black and white illustrations. These are frequently redrawn from classic sources and although not always very elegant they serve well enough. A particular strength is the abundant flowcharts, time lines, and tables that are used to describe methods for aging embryos, give detailed information on teratogens, and describe complicated patterns of differentiation. The flowchart on hematopoiesis is a big one, and gives the factors driving each step. No one could remember all this. It’s the idea that
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counts. And don’t tell me it doesn’t matter. Some years ago, a person close to me discovered he had colonies of carcinoma cells scattered throughout his red bone marrow but not elsewhere. There were only the vaguest explanations for the precision of this distribution. What subtle interplay of adhesion molecules, growth factors, and the like could account for this? Had we known, he might have lived. The authors, like the rest of us, are not infallible: they cling to the odd belief that the binucleate cells of the cow’s placenta disappear after 40 days gestation and their description of the origin of the necrotic tips of the pig’s placenta is plain wrong. I know this is a minor point but, because I wrote about it long ago, it touched a nerve. In my defence I should say that the roots of the misunderstanding go deep and can be found in the authors’ illustration of the fetal membranes of artiodactyls supposedly at midgestation. This shows a huge extraembryonic celome, a structure that had long since been obliterated; and worse, the extraembronic celome entirely separates the allantois from the overlying chorion. This would have made the evolution of eutherian mammals impossible. I was also a bit surprised to find the unqualified implication that there are male germ cells in the ovaries of freemartins. This is indeed an exciting idea, but surely controversial. It would have been better to talk about Mullerian inhibiting factor. Since this book landed on my desk, I have had 2 requests for embryological information, one about the development of the equine colon and one the pattern of increase in fetal mass during gestation. In both cases the book was a near miss. The development of the equine cecum was well described but not the colon, and there are exhaustive time lines for fetal length but not weight. It is hard to win them all. In general, this is a fine work. It would benefit from sections on fetal growth and the changes that occur at birth. Often our favorite texts are those that have mellowed through much reading and many editions. This book just might be the foundation of such a lineage. It is not cheap: something must be done about the price of textbooks. Reviewed by Peter Flood, BVSc, MSc, PhD, MRCVS, 818–5th Avenue North, Saskatoon, Saskatchewan S7K 2R8. CVJ / VOL 50 / FEBRUARY 2009
