Life as it's happening
A zygote is created when a sperm joins with an oocyte and fertilisation happens.
- first cleavage
- second cleavage; development into a 4-cell embryo
- development into an 8-cell embryo
- The cell membranes start fading away and fusion of the cells (blastomeres) ensues. This stage is also called 'compaction'.
- transition to blastocyst stage: the compacted embryo expands while the embryonic cells move to the preiphery and allow the formation of a caity called 'blastocoele'. The peripheral cells will develop into placental tissue and membranes, while the cells of the inner cell mass will develop into the fetus.
The embryo will subsequently hatch and infiltrate into the endometrial lining of the uterus.