In vitro culture of embryos of the guppy, Poecilia reticulata.

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.