Advantages and disadvantages of the use of Xenopus laevis embryos and zebra fish as alternative methods to assess teratogens

Traditional teratological protocols in mammals are mandatory for pharmaceutical and chemical product registration, but require hundreds of animals and are complex and money/time-consuming. Among alternative methods, low vertebrate (the teleost zebrafish and the amphibian Xenopus) whole embryo developmental toxicological tests appear evolutionary closer to humans than invertebrates and produce more useful data for human health extrapolation. At least during early stages, in fact, all vertebrate embryos share, from both morphological and molecular point of view, developmental pathways. By consequence similar toxicological responses of embryos to toxicant are expected. Advantages and disadvantages of these two alternative whole organism tests are briefly reviewed.