Regional specificity of glycoconjugates in Xenopus and axolotl embryos.

This paper reviews work on the presence, synthesis and developmental regulation of glycoconjugates (proteoglycans, glycoproteins and glycolipids) in the early amphibian embryo. In the axolotl there is little regional specificity of protein synthesis until the tailbud stage, but substantial regional specificity of glycoprotein synthesis from the end of gastrulation. Glycolipid synthesis is more uniform although a number of unique species are made in the epidermis. Isolated explants from axolotl early gastrulae show three types of behaviour in terms of glycoprotein synthesis, corresponding to the classical germ layers. Xenopus embryos at this stage show a higher degree of mosaicism. Changes of glycoprotein synthesis in response to mesodermal or neural induction follow the predicted course depending on the regional character of the induced tissue. The regional binding patterns of a number of lectins and monoclonal antibodies specific for particular carbohydrate determinants are presented and their significance discussed.