The Effects of β-Mercaptoethanol on the Morphogenetic Movements of Amphibian Embryos
The inhibition by β-mercaptoethanol of morphogenesis in amphibians, freshwater hydra, planarians and regenerating tadpoles, has already been reported by one of us (Brachet, 1958, 1959a, b, c). The present work provides a closer analysis of the biological specificity of j8-mercaptoethanol with regard to the different movements which produce gastrulation in amphibians: invagination, epiboly, convergent stretching and ingression. The main result, obtained with Pleurodeles, was that gastrulation is completely inhibited by M/100 β-mercaptoethanol. Lower concentrations (M/300) permit more complete development, but the resulting embryos are abnormal. β-Mercaptoethanol interferes with neural tube formation, but has less effect on the development of the notochord and the mesodermal somites. It was further noted that, when embryos are treated at very early stages (1–2 cells, young blastulae), the blastocoele seems to collapse and the ectoblast of the animal pole is deeply puckered.