The beginnings of developmental biology in Swiss universities

This contribution describes the pioneer work in Developmental Biology, initiated by Swiss scientists. The anatomist W. His (1831-1904) deserves credit as the founder of "Descriptive Embryology". Using novel microscopical techniques, he documented the formation of the embryonic body of various vertebrates as an approach to reveal the mechanisms of morphogenesis. Based on studies of the chick embryo, he designed a fate map of the germ-disk, comprising organ-forming regions, from which the corresponding embryonic structures originate. F. Baltzer (1886-1974) initiated original studies on the role of nuclear and cytoplasmic factors in the development of sea urchin hybrids and newt merogons. Through his experiments on interspecific and intergeneric chimeras of amphibians, he further contributed to the emerging field of "Developmental Genetics". F.E. Lehmann (1901-70) inaugurated work on "Chemical Embryology" and later moved to "Cell Biology". His discoveries on stage- and regional-specific inhibition of morphogenesis by LiCl in newt embryos were important for the understanding of malformations. Further studies regarding the action of cytostatic substances on tail regeneration in tadpoles were intended to yield information on growth control. Original contributions to "Experimental Embryology" were also made by R. Geigy (1902-1995), who devised an ingenuous procedure for obtaining sterile Drosophila flies by UV-irradiation of eggs. In later studies on anuran metamorphosis, he discovered that the morphogenetic effects of the metamorphic hormones are organ-specific and that competence of the larval tissues to respond to thyroid hormone is stage-dependent.