title: Ionophore-induced cell shape changes in Xenopus early embryos.
abstract: Local application of the Ca++ ionophore A23187 to the intact lateral ectoderm of Xenopus early neurulae causes changes in the shapes of the cells; ectoderm cells lose their relatively flat surfaces and become rounded. Some of the affected cells form microvilli. Ionophore was found to induce cell shape changes in ectoderm in the presence of cytochalasin-B, suggesting that microfilaments are not involved. Ionophore was also found to induce cell shape changes in neurula ectoderm when it was applied to embryos cultured in Ca++- and Mg++-free medium containing EDTA, suggesting that extracellular Ca++ is not utilized in the ionophore-induced cell shape changes. Similarly, the Ca++ antagonists D-600, which reduces the entry of Ca++ into cells, and TMB-8, which antagonises certain intracellular Ca++-dependent functions, did not inhibit the effects of A23187 on amphibian embryos.
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D003571:Cytochalasin B / Q000494:pharmacology; D004475:Ectoderm / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D004492:Edetic Acid / Q000494:pharmacology; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000187:drug effects; D005260:Female; D005711:Gallopamil / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008855:Microscopy, Electron, Scanning; D014981:Xenopus
chemical_list: D000001:Calcimycin; D005711:Gallopamil; D003571:Cytochalasin B; D004492:Edetic Acid; D008274:Magnesium; D002118:Calcium