~ ] O O K [ ] ~ E V I E W S

Cellular Basis of Morphogenesis (CIBA

Foundation Symposium 144)

edited by D. Evered and J. Marsh, John Wiley & Sons, 1989. £32.50 (viii + 307 pages)

ISBN 0 471 92306 0

It must have been an exciting few days in Autumn 1988 when an elite group of researchers got together in Madrid. This volume contains the manuscripts present- ed at this symposium together with a transcript of the ensuing discussion. This commendable openness helps highlight contro- versial scientific issues, and pro- vides a little entertainment along the way. The book is about animal development, and students of this discipline will find it irresistible, but I expect it will find an audi- ence among nonspecialists as well.

Fourteen years ago another CIBA symposium covered similar ground, and several of the partici- pants at this symposium were present then. Inevitably, there is some reflection on the progress made in those years, and there is a hint of satisfaction: the genetic approach as well as biochemistry and tissue culture have been very successful. But these men and, happily, women are not com- placent and the discussion is just as critical as it was 14 years ago. It seems that some simple morpho- genetic processes, like the formation and interpretation of the gradient of bicoid protein, are close to solution, but other phenomena, like size regulation, remain mysterious. There is plenty of work left to do.

Even though many of these papers review work that has been published in the research litera- ture, there is so much here that no-one is likely to come away without something new. For instance, I was fascinated to learn that a determinative activity associated with the teloplasm

during leech development is quite likely to be due to polyadenylic acid. Some intriguing biochemistry must lie between the molecule and the resultant cellular behavior.

Everyone seems content to call this sort of substance a determi- nant. But when a localized molecule diffuses and forms a concentration gradient Turing's term 'morphogen' and the language of positional information are invoked. Much discussion centered around these now not so mythical molecules. In general this emphasized that finding a mor- phogen does not necessarily lead to a satisfactory understanding of patterning. For instance, growth- factor-like molecules are produced by the cells of the vegetal pole of the Xenopus embryo and induce mesoderm. Is diffusion of these morphogens from their source an adequate explanation of the sig- nals that pattern the mesoderm? Cooke argues persuasively that it is not and that other factors must be considered to account for mesoderm pattern. These argu- ments often emphasize the role that theory has to play in this science.

Most of the work reported here addresses the question of how cells are allocated to particular fates, or states (but that's another

story, and worth reading). How these instructions are executed to generate physical form is also a very important question. I was disappointed that there was not more about these aspects of mor- phogenesis. There is, however, a paper by Takeichi and colleagues about a class of molecules they have characterized, the cadherins, which mediate calcium-dependent cell adhesion. Different types of cadherin present on different tissue types seem to cause differ- ential adhesivity, which is import- ant for segregating tissues from one another. Incidentally, any geneticist who feels overconfident should read this paper: bio- chemical approaches can outpace genetic ones, and they do.

There is a lot of fascinating science in this book. I for one will be reading it over for some time to come, and if things continue at the present rate it will be dated by the time I finally put it down. But by then I hope another CIBA sym- posium will allow me to eaves- drop on the third in this occasional series.

KEN HOWARD

Howard Hughes Medical Institute, Columbia University Neurobiology and Behavior Center,

New York, IVY 10032, USA.

Metastasis (CIBA Foundation Symposium 141)

edited by G. Bock and J. Whelan, John Wiley & Sons, 1988, £30.50 (ix + 255 pages)

ISBN 0 471 91513 0

Metastasis, the spread of a primary tumour to distant sites, is generally what kills a cancer patient, because it puts the cancer beyond reach of effective therapy by local excision or irradiation. Clinicians are therefore concerned with the diagnosis and treatment of cancer before metastasis has occurred;

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whether screening can detect can- cers at this stage; the prediction that metastasis has already occurred, and the pattern of spread, in the planning of primary treatment for a cancer; and in the treatment of metastasis after the event. Biologists, on the other hand, are fascinated by metastasis because it is a strildng example of the breakdown of the rules of tissue organization, and these rules and how they are kept is a central problem of biology.

Biologists concentrate for the most part on how metastatic can- cer ceils leave their native tissue and how they establish themselves elsewhere. But this is not quite what clinicians are interested in: for the most part, they do not seek to influence the process of