Expression of Oct4-related genes in cloned and control embryos
| Embryo type . | Developmental stage after 4 days of culture . | Number of embryos studied . | Percent of embryos with all 11 tested genes activated . |
|---|---|---|---|
| Cumulus clones | Pre-morula | 9 | 0% |
| Morula | 8 | 25% | |
| Blastocyst | 48 | 62% | |
| ES cell clones | Pre-morula* | N/A | N/A |
| Morula | 4 | 100% | |
| Blastocyst | 14 | 100% | |
| Control embryos | Four-cell embryo† | 6 | 100% |
| Morula† | 6 | 100% | |
| Blastocyst† | 7 | 100% | |
| Parthenogenetic blastocysts | 22 | 100% | |
| In vitro fertilized blastocysts | 8 | 100% |
| Embryo type . | Developmental stage after 4 days of culture . | Number of embryos studied . | Percent of embryos with all 11 tested genes activated . |
|---|---|---|---|
| Cumulus clones | Pre-morula | 9 | 0% |
| Morula | 8 | 25% | |
| Blastocyst | 48 | 62% | |
| ES cell clones | Pre-morula* | N/A | N/A |
| Morula | 4 | 100% | |
| Blastocyst | 14 | 100% | |
| Control embryos | Four-cell embryo† | 6 | 100% |
| Morula† | 6 | 100% | |
| Blastocyst† | 7 | 100% | |
| Parthenogenetic blastocysts | 22 | 100% | |
| In vitro fertilized blastocysts | 8 | 100% |
Up to 85% of ES clones arrest as one to two-cell embryos probably because of cell cycle incompatibility with the oocyte. The remaining 15% of ES cell clones progress to morula and blastocyst stages of development. Therefore a pre-morula class of four- to 16-cell embryos is missing among the ES cell-derived clones.
Control embryos collected at indicated stages of development.