 |
 |
 |
| fertilized egg (zygote) |
2-cell stage |
4-cell stage |
 |
 |
 |
| 8-cell stage | 16-cell stage |
morula |
 |
 |
 |
| blastula | gastula | gastrula |
| Number |
Structure |
| 1 |
blastocoel (cavity) |
| 2 |
endoderm |
| 3 |
ectoderm |
| 4 |
blastope |
