Determination of anterior endoderm in Xenopus embryos

Crafts of anterior endoderm from embryos at stage 28 or later developed acc ording to their fate (i.e., anterior) when transplanted posteriorly. Conver sely, grafts from earlier embryos developed according to their new location (i.e,, posterior). However, endoderm grafted along with its mesodermal and ectodermal sheath retained its fate regardless of the stage of the donor. We conclude that anterior endoderm in Xenopus embryos is determined at abou t stage 25 under the influence of mesoderm. (C) 2000 Wiley-Liss, Inc.