Dy-mystifying the IVF Laboratory – What is ICSI?
Matt Wiltshire is a Monash IVF Embryology Supervisor and a fantastic colleague and friend. We have decided to de-mystify some of the IVF related terms and make them easier to understand and provide you an insight into what we do in the IVF laboratory.
We decided to start things off with what is ICSI?
ICSI is an acronym standing for Intra-Cytoplasmic Sperm Injection – we pronounce it to sound like “Ik-See”. I know it may sound like technical jargon, and I know that sometimes medical and scientific terms can be overwhelming; but in fact, it is very easy to understand and does exactly what it stands for.
So, let’s break the term down:
“Intra”- means internal
“Cytoplasmic” – that is the content of a cell
“Sperm Injection”- well fortunately those two words are actually in English
So, we basically inject a single sperm into the middle of an egg – and that is ICSI.
Following your egg retrieval, the scientists in the IVF laboratory will collect and count the number of eggs your doctor and scientist have recovered. The laboratory will then culture your eggs in special incubators and in a special fluid for a couple hours prior to the next step of assessing egg maturity. When the eggs are first collected they are surrounded by supporting cells called the Cumulus cells. They are called Cumulous cells because under the microscope they look a bit like the cumulous clouds we see up in the sky. These cells partially obscure the view of the egg, but are there to provide a critical role in developing the egg and in maturing the egg. In order to do the ICSI procedure we need to assess the eggs maturity, as only the mature eggs can be fertilised by the sperm. To assess the maturity of all the eggs we collect, we gently remove the supporting Cumulous cells in a process called “Denuding”.
Once the Cumulous cells are removed, we are then able to grade the eggs as either being mature, and therefore suitable for injection; or premature and not suitable for injection. To inject the egg with a sperm, we set up some very specialised equipment under the microscope. This equipment allows us to select and collect a single sperm; and we use other equipment to hold onto the egg and keep it immobile, so as to allow us to inject the sperm into the egg.
This technique takes many months to learn and years to master and is the pinnacle of an embryologists training. Once the needles have been set up and aligned we search for the best and most suitable sperm to inject into the egg. When searching for sperm, scientists will assess the sperm’s appearance (morphology) and its motility and the way it is swimming. In a way it’s a bit like the AFL drafting process, where we look for the best of the best. It is not uncommon for us, on occasion, to literally spend hours and hours to find the most perfect sperm to give us the best possible result. It is important to remember that we select the best sperm to fertilise each and every egg we collect.
Whether a semen sample has hundreds of millions of sperm or if we are searching for just a few sperm from a testicular needle biopsy for example; we are meticulous and obsessive in our procedures to find and get what we want.
Once the sperm are found, we use an injecting micropipette to collect a sperm. At the same time, the egg is held in place with the holding pipette. The scientist will then carefully and delicately insert the needle into the egg to deposit the sperm inside the egg.
After all your mature eggs have been injected they are cultured in our special incubators and assessed the next day for fertilisation. Your nurse or scientist will call with your fertilisation results and the next steps after this.