[Production of partial blastulas by parthenogenesis in Xenopus]

In mature Xenopus eggs, the cell cycle can be triggered by pricking the egg or by an electric shock. However, no cleavage occurs unless centriole-containing fractions or isolated centrosomes are injected at the time of egg activation. We have obtained for an average of one heterologous centrosome injected per oocyte a complete parthenogenetic development. We also observed that the success rate of blastula formation declined linearly with the time elapsing between oocyte activation and centrosome injection. Moreover, in most cases, large areas of the blastulas remained uncleaved, interfering with gastrulation and blocking further development.