Reviewed by Ashley Wong, MS, Clinical EmbryologistCheckmark | Last updated: April 17, 2020

What Does Blastomere Mean?

A blastomere is a cell that is created in the early stages of division in a fertilized egg. These divisions are called cleavage divisions, and the cells created by each cleavage-stage are called blastomeres.

During in vitro fertilization (IVF), blastomeres are evaluated and processed for a series of important procedures, including embryo grading and blastomere biopsy.


FertilitySmarts Explains Blastomere

Blastomeres or cells are created in the first stage of embryonic development when the fertilized egg transitions from one cell to 2-cell, 4-cell, 8-cell, and 16-cell variants through a process called cell division.

In Vitro Fertilization

During in vitro fertilization (IVF) procedures, blastomeres are evaluated through a process called embryo grading. The embryo grading process allows scientists and physicians to determine how embryos are developing and which are the most appropriate for transfer for the uterus. Embryo grading is a standard IVF procedure and regulated by testing standards.

Blastomere Biopsy

Blastomeres are also used for the blastomere biopsy, also known as an embryo biopsy. This procedure is performed as part of preimplantation genetic screening (PGS) on a 3-day old embryo, involving scientific testing during stage 4, 6 and 8 cells. The blastomere biopsy can indicate if chromosome abnormalities or genetic defects are present in the developing embryo.

This is a voluntary procedure that is typically only conducted if the embryos are considered at risk for adverse conditions, based on:

  • Maternal age
  • Previous pregnancy history
  • Parental health conditions

Most biopsy today occurs on a more developed embryo as it may provide a more definitive answer since more than one cell is tested and might be less developmentally detrimental to the embryo.


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TreatmentEggSpermIn Vitro Fertilization (IVF)Embryo Development

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