Synthesis of laminin-related polypeptides in oocytes, eggs and early embryos of the amphibian Pleurodeles waltlii.

In the amphibian Pleurodeles waltlii, lamininrelated polypeptides (amphibian-LN) are present in the extracellular matrix underlying the blastocoel roof of gastrulating embryos. Immunoprecipitation with affinity-purified anti-laminin antibodies demonstrated that amphibian-LN is synthesized in oocytes (from stage III onward), eggs and throughout early development. At the late blastula stage, when experiments were carried out with animal and vegetal halves, there were no regional differences in the pattern of amphibian-LN synthesis. The results obtained with transcription inhibitors suggest that throughout pregastrula stages, amphibian-LN is a translation product of stored maternal mRNA. Finally, having compared amphibian-LN and fibronectin synthesis, it is concluded that both extracellular glycoproteins have a common pattern of synthesis.