The role of Ca2+ in the regulation of embryogenesis in early amphibian and echinoderm embryos

It is difficult to measure intracellular calcium concentrations in dividing embryos and, furthermore, these interact with pHi and with cyclic nucleotides. Nevertheless, the evidence currently suggests that changing [Ca2+]i levels probably do not have a major role in controlling normal cell-to-cell communication and so do not integrate cell division during programmed cleavage in amphibian embryos. However, treatments that are known or expected to raise artificially cytoplasmic calcium to relatively high levels cause abnormal embryogenesis, probably via the uncoupling of intercellular communication of the blastomeres, and also cortical contractions in early echinoderm and amphibian embryos.