[1] In humans, blastomere formation begins immediately following fertilization and continues through the first week of embryonic development.
The two-cell blastomere state, present after the zygote first divides, is considered the earliest mitotic product of the fertilized oocyte.
Once this begins, microtubules within the morula's cytosolic material in the blastomere cells can develop into important membrane functions, such as sodium pumps.
[5] The division of blastomeres from the zygote allows a single fertile cell to continue to cleave and differentiate until a blastocyst forms.
[6] During the 8-cell differentiation period, the blastomeres form adheren junctions, and subsequently polarize along the apical-basal axis.
The adhesive lateral junction is then formed, and the blastomere is flattened to establish the apical cortical domain.
Once the transition begins to a 16-cell mass, the apical cortical domain disappears, but elements of polarity are preserved.
This allows for approximately half of the blastomeres to inherit polar regions that can rebuild the apical cortical domain.
Studies have shown that these giant cancer cells are often also the genetic equivalent to somatic blastomeres.
[14] Oftentimes, clinicians and researchers will use blastomere biopsies in at-risk pregnant women as a way to test for genetic disorders.