For some couples, arriving at the miracle of birth is more complex than sperm + egg = embryo = pregnant. The human body is incredibly complex, and few processes are as complicated as human reproduction.
For example, consider the first five days in the reproduction process:
Day 0 – Egg meets sperm in the fallopian tube. Sperm penetrates egg.
Day 1 – Fertilization occurs and a zygote forms, which includes DNA from both the male and female.
Day 2 – The zygote has evolved into an embryo. Cell count is now four.
Days 3 to 5 – Even more growing as the cells split. There are now eight cells. The embryo leaves the fallopian tube and enters the uterus.
Day 5– Embryo hatches, blastocyst embryo erupts and implants into the uterine wall, and a woman is deemed pregnant.
There’s clearly a lot happening during those five days, and reproductive medicine experts would tell you there’s a lot of ways things can go wrong. For some couples, fertility challenges may not even have anything to do with either partner. Sometimes, the embryo itself has trouble doing its part.
For instance, one little known fact is that a human embryo must actually “hatch” from its surrounding shell – the zona pellucida – for a pregnancy to occur. Experts call this “embryo eruption.” But some embryos just can’t hatch by themselves.
For patients at the University of Minnesota Physicians Reproductive Medicine Center whose embryos are having trouble hatching, experts like embryologist Christopher De Jonge, Ph.D., H.C.L.D., can help.
De Jonge explained there are a number of reasons why an egg doesn’t hatch naturally. The most common: the outer shell of the egg is simply too thick for the embryo to break through on its own.
“If a woman’s embryo cannot hatch on it’s own, she won’t become pregnant,” said De Jonge. “But we can help with a technique called ‘assisted hatching,’ a post-fertilization micromanipulation technique.”
To help a human egg hatch, it first has to be harvested. De Jonge then moves the egg to a very scifi-esque lab to incubate. Every surface it will touch in the lab is set at 37 degrees Celsius (body temperature) and the incubator is kept at 5.8 oxygen (O2), 6.2 carbon dioxide (C02).
“Everything is regulated to be like the human body,” said De Jonge. “Just because this procedure is happening outside the body, doesn’t mean the egg should feel any differently than if it were still inside.”
On day three of fertilization, De Jonge uses a high tech laser beam to create a small hole in the zona pellucida to allow the embryo to emerge.
The zona pellucida of the egg has a dense and tough inner layer, but a soft, fluffy outer layer. Tiny in size, the egg could be easily damaged if burning the hole is not handled with precision and care.
“The laser we use is high intensity, and creates concentric, predictable rings with calculable heat,” explained De Jonge. “The laser skims the top of the egg, far enough away from all the good stuff happening inside.”
On day five, the blastocyst is returned to a patient’s uterus where it will erupt, attach and grow for the next 38 to 40 weeks.
De Jonge, whose lab has had the laser for a little over a year, believes using a laser is the safest choice.
“Prior to the laser, post-fertilization micromanipulation options were mechanical tearing or a pipet with acid,” De Jonge said. “The laser’s precision makes it a more accurate way to perform post-fertilization micromanipulation.”