The rich variation in adult color patterns of male guppies (Poecilia reticulata) has attracted the attention
of geneticists and ecologists for almost a century. Studies on their embryogenesis, however, have been
limited by the fact that guppies are live bearers. We have observed normal development after explantation
of guppy embryos from the ovary of pregnant females at various times after last parturition, and found that
development of each batch of eggs is slightly asynchronous, most likely due to asynchronous fertilization.
We have cultured explanted embryos in vitro and continuously observed their development. Although
embryos explanted a few days after fertilization survived up to 4 weeks in culture, they did not complete
their development. In contrast, embryos explanted at late stages of gestation could hatch and develop to
fertile adults. Our embryo culture techniques overcome some of the limitations of using livebearers as study
objects, and they allow continuous observation of and accessibility to live embryos at all stages.