Abstract
Electron probe X-ray micrcanalysis of calcium was performed on 8-cell embryos, morulae and blastocysts of mice. (1) In normal 8-cell embryos and morulae, calcium was detected on the cell membrane, but not in other parts such as the nucleus, cytoplasm, zona pellucida and perivitellin space. In blastocysts, calcium was found only on the trophoblastic cell membrane facing zonae pellucidae and inner cells. (2) Cultured in calcium-free medium, 8-cell embryos stopped growing and there was no calcium detected in any portion of the embryos. These results suggest that the calcium on the cell membranes of blastomeres in 8-cell embryos and morulae and on those of trophoblastic cells in blastocysts plays an important role in the formation of blastocysts.
