Range: 5E-9 to 8E-9 mol
||African clawed frog Xenopus laevis
||Slack C, Warner AE, Warren RL. The distribution of sodium and potassium in amphibian embryos during early development. J Physiol. 1973 Jul232(2):297-312 SummaryPubMed ID4737869
||Summary: "1. Intracellular and intercellular concentrations of sodium and potassium have been measured in pregastrular embryos of Xenopus laevis and
Amblystoma mexicanum. Calcium and magnesium contents have also been
||Summary: "3. Embryo calcium and magnesium concentrations show no significant variations prior to gastrulation. Average calcium concentrations for the different stages range from 5 to 8 m-mole/l. embryo, magnesium concentrations lie between 12.4 and 17 m-mole/l. embryo."