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Somewhere in a laboratory right now, under a microscope powerful enough to resolve a single cell, a scientist is making a decision that could change a family forever.

They are working in near-silence, in a carefully controlled environment where temperature, pH, and humidity are monitored to decimal-point precision. In front of them, suspended in a drop of culture medium, is a human blastocyst - a five-day-old embryo roughly the size of a grain of sand. And they are about to take a biopsy.

This is the world of the embryologist, and on World Embryologist Day, we think it is worth stepping inside it.

 Who Are Embryologists?

An embryologist is a specialist scientist who works in the IVF laboratory - responsible for every stage of embryo development outside the body. Their work begins before fertilisation and continues until the moment an embryo is transferred into the uterus, or frozen for future use.

Their daily tasks include:

• Preparing eggs retrieved from the ovaries for fertilisation
• Performing Intracytoplasmic Sperm Injection (ICSI) — injecting a single sperm directly into an egg using a glass needle thinner than a human hair
• Monitoring fertilisation and daily embryo development
• Grading embryos based on morphology (their appearance and cell structure)
• Performing embryo biopsy for Preimplantation Genetic Testing (PGT)
• Cryopreserving (freezing) and thawing embryos

It is painstaking, high-stakes, highly skilled work - and much of it happens invisibly, behind closed laboratory doors, while patients wait with hope and anxiety in equal measure.

The IVF Laboratory: A Carefully Controlled World

The IVF lab is one of the most controlled environments in medicine. Human embryos are extraordinarily sensitive - small fluctuations in temperature, light exposure, or gas composition can affect development. It is also where one of the most significant advances in reproductive medicine takes place: the embryo biopsy.

What is Embryo Biopsy?

Embryo biopsy is the procedure that makes Preimplantation Genetic Testing (PGT) possible. It involves removing a small number of cells from a developing embryo so that its DNA can be analysed - without harming the embryo's ability to develop into a healthy baby.

The technique has evolved significantly over the past three decades. Today, the preferred approach is trophectoderm biopsy (the outer layer that will become the placenta) at the blastocyst stage (Day 5 or 6 of development). The embryologist uses a laser to cut through the zona pellucida (the outer shell of the embryo), then a fine glass pipette to gently aspirate 5-10 trophectoderm cells.

These trophectoderm cells are then sent to the genetics laboratory for analysis. The embryo itself is frozen immediately - a process called vitrification - while awaiting results.

From Biopsy to Result: How PGT Works

Once the biopsied cells arrive in the genetics laboratory, the DNA is extracted, amplified, and analysed using Next Generation Sequencing (NGS).

PGT-A (Preimplantation Genetic Testing for Aneuploidies) examines all 23 pairs of chromosomes in the biopsied cells, checking for extra or missing chromosomes - a state called aneuploidy.

Chromosomal aneuploidy is the single most common cause of:

• Failed embryo implantation
• First-trimester miscarriage
• IVF cycle failure

The likelihood of aneuploidy increases significantly with maternal age. Research published in Fertility and Sterility found that in women under 35, approximately 40% of blastocysts may be aneuploid - rising to over 80% in women over 40.¹

PGT-A identifies which embryos are euploid (chromosomally normal), allowing the fertility team to prioritise these for transfer. The impact on outcomes is clinically significant:

• Increased live birth rates per transfer
• Reduced miscarriage rates
• Fewer IVF cycles needed to achieve a successful pregnancy
• Shorter time to pregnancy

Behind Every Result: A Human Story

It is easy to describe PGT in clinical terms - chromosomes, sequencing, euploid, aneuploid. But behind every result is a person, or a couple, who has been through something profoundly difficult to get to this point.

The woman who has had three IVF cycles, each ending in a negative test. The couple who lost a pregnancy at 18 weeks to a chromosomal condition they did not know was in their family. The woman is 42 and knows her time is limited and wants to give herself every possible chance.

For these people, PGT is not an abstract technology. It is hope, made visible.

To learn more about Preimplantation Genetic Testing at Next Biosciences, visit nextbio.co.za or contact our team on 011 697 2900 or genetics@nextbio.co.za. Our in-house genetic counsellor is available to guide you through your options.

 

References

1. Franasiak JM, Forman EJ, Hong KH, et al. The nature of aneuploidy with increasing age of the human egg: a review of 15,169 consecutive trophectoderm biopsies evaluated with comprehensive chromosomal screening. Fertility and Sterility. 2014;101(3):656–663.