Changes in alkaline phosphatase activity in dissociated cells of Xenopus laevis embryosin culture

Xenopus laevis embryos at the blastula stages were dissociated into cells and cultured in either Stearns' complete medium or Ca^^2+-Mg^^2+ free medium, and then the activity of alkaline phosphatase in both cells was determined. In the complete medium the dissociated cells from the mid-blastula embryos (stage 8) formed aggregates and showed a normal increase in enzyme activity. The cells in the Ca^^2+-Mg^^2 free medium did not form aggregates at all and failed to increase the activity, even when they divided as active as those in the complete medium. The cells in the Ca^^2+-Mg^^2 free medium remained isolated, but after being transferred into the complete medium they formed aggregates and increased the activity as well. The rate of increase in activity, however, became low, when the cells were cultured in the Ca^^2+-Mg^^2 free medium for more than two hours. The simillar results were obtained with the cells from the late-blastula embryos (stage 9) . These results are considerably different from the previous results obtained in the same system.