Table 5.
Definitions of investigated parameters
| Parameters | Definition | Assessme |
|---|---|---|
| 1st and 2nd nuclei appearance | Appearance of 1st and 2nd nucleus at 2-cell stage. | Time-point |
| 1st and 2nd nuclei disappearance | Disappearance of 1st and 2nd nucleus at 2-cell stage. | |
| Divisions from 2 cells to 8 cells | Each division is a complete separation of two daughter cells enclosed by their own cytoplasmic membrane | |
| Final division | The final cleavage division to ≥9 cells before initiation of compaction | |
| Compaction | The first fusion of two cell boundaries followed by a decrease in embryo diameter | |
| Morula | The compaction process is complete for all cells. All cell boundaries are unclear. | |
| Early blastocyst | The initiation of blastulation when a blastocoel is visible (bl1) | |
| Full expanded blastocyst | The blastocoel cavity fills out ≥50 % of the embryo and an inner cell mass i well defined (bl3) | |
| Hatching blastocyst | The trophectoderm herniation (bl5) through the zona Pellucida. | |
| Hatched blastocyst | The embryo has full escaped the zona Pellucida (bl6) | |
| Multinucleation | Multinucleate at 2-cell stage | Binary |
| Direct cleavage to 3 cell stage | t3-t1 <5 h | |
| First cytokinesis | Appearance of cleavage furrow or considerable elongation (>15 %) at one-cell stage until complete separation. | Duration |
| Synchrony of nuclei appearance at 2-cell stage | Time from the appearance of 1st and 2nd nuclei at 2-cell stage | |
| Synchrony of nuclei disappearance at 2-cell stage | Time from the disappearance of 1st and 2nd nuclei at 2-cell stage | |
| Duration of 2-cell stage | t3-t2 | |
| Duration of 3-cell stage | t4-t3 | |
| Duration of the 4-cell stage | t5-t4 | |
| Duration of 2nd cleavage division | t4-t2 | |
| Duration of 3rd cleavage division | t8-t4 | |
| Synchrony of the 3rd cleavage division | t8-t5 | |
| Duration of 4th cleavage division | t ≥ 9-t8 | |
| Blastulation (bl3-bl1) | Duration from early to full expanded blastocyst (bl3-bl1) |
The time-point assessment was applied to the dynamic parameters. Measurement of a certain duration was subsequently calculated as the interval between two time-points. Assessment of binary values yes and no was applied to morphologic parameters