INTRODUCTION
The Mead laboratory studies the development of the hematopoietic system in the early vertebrate embryo. We use the frog as a developmental model system as it offers many advantages for the study of early events in embryonic patterning and organogenesis. We currently use two species of frogs, Xenopus laevis and Xenopus tropicalis.

Xenopus laevis: This aquatic frog from South Africa has been an important vertebrate model system for the last fifty years. The frogs are easy to keep in the laboratory environment and their large eggs are suitable for a wide variety of embryonic manipulations. Genetic manipulation of this species is impractical however as they have a long generation time (~1 year) and a tetraploid genome.

Xenopus tropicalis: This small aquatic frog from West Africa is a close relative of X. laevis. It shares many of the features that make this genus of frog a useful model for vertebrate embryology. In addition, X. tropicalis have a short generation time (~4-5 months) and a diploid genome. These features will allow genetic manipulation of the X. tropicalis genome. The combination of genetics and classical embryology make this an attractive model system for the study of early vertebrate development.

AIM
Our laboratory has focused on insertional mutageneis approaches (retroviruses and transposons) to modify the frog genome. The goal of these web pages is to disseminate information on (i) the progress of these mutagenesis approaches, (ii) frog husbandry and related issues and (iii) the availability of transgenic/mutant frog lines and plasmid constructs will be displayed in a regularly updated database.