This work which was published to mark the tenth anniversary of the collaboration between the Institut Pasteur and the Riken Institute in Japan, covers a number of research fields in which both laboratories are active: precocious development in mice and the effect on them of disactivating genes, nuclear oncogenes and their role in controlling cell division, and the molecular bases of bacterial and viral infections. There are also chapters dealing with specific aspects of immune recognition, the genetics of sexual determination in humans and a new technique for studying the human genome. This book is intended for researchers and physicians in the fields of immunology, genetics, bacteriology/virology, cancerology, developmental biology, cellular biology and neurobiology.