| Tetraploidy was induced in embryos of Ruditapes philippinarum by treating the eggs with cytochalasin B. (CB). Two treatment times were found to be effective in inducing tetraplidy : 0 to 10 minutes after insemination (before formation of the first polar body) and 45 minutes after insemination (just before the first cleavage). Treatments, started 5 and 45 minutes after insemination, produced 64.4 ± 7.8% and 28.3 ± 2.3% tetraploid embrios, respectively, after 6 hours (on the average over 3 experiments). However, no tetraploids were detected in 4-month-old spat. Sperm entry delayed by the CB could be involved in induction of tetraploidy by early treatment. |
