The development of modern medicine has contributed to clarifying the etiology and treatment of various diseases as well as to improving public health and welfare, and basic biological research has discovered a great deal about the underlying mechanisms at work. However, there are still many diseases which remain mysterious and incurable, and biological processes which are still imperfectly understood. In order to promote research in medicine and biology, non-governmental funding, as well as government support, is very important. The Japan Medical Research Foundation has been in existence since October 1973 in order to meet such needs with aid from non-governmental financial sources. One of the Foundation's main activities is to hold annual symposia and seminars on various diseases and research problems. To elucidate the mechanisms of the development of the nervous system in mammals is one of the most challenging problems for researchers in the field of developmental biology. Are there any formulae in the develop­ ment of this complicated system? What factors are involved genetically and environmentally? Only a few questions have been answered so far.