Cytoplasmic and molecular reconstruction of Xenopus embryos: synergy of dorsalizing and endo-mesodermalizing determinants drives early axial patterning.

Ablation of vegetal cytoplasm from newly fertilized Xenopus eggs results in the development of permanent blastula-type embryos (PBEs). PBEs cleave normally and develop into a very simple tissue consisting only of atypical epidermis. We tried to restore complete embryonic development in PBEs by cytoplasmic transplantation or by mRNA injection.

Anteroposterior patterning in Xenopus embryos: egg fragment assay system reveals a synergy of dorsalizing and posteriorizing embryonic domains.

Two distinct types of axis lacking embryos resulted from partial deletion of the vegetal part of early one-cell-stage embryos. When the deleted volume was 20-40% (relative surface area), the embryos underwent ventral-type gastrulation and formed ventral mesodermal tissues. When the deleted volume was more than 60%, the embryo did not gastrulate nor make mesodermal structures (M.