The healthiest sperm cells tend to have a certain shape and size, particularly an oval head and a long tail which they use to push themselves along as they swim. Infertile men often make fewer such sperm so that sperm selection for ICSI is important.
Next consideration is sperm motility – a sperm cell’s motility is its ability to move itself around and penetrate an egg. This depends on the length and size of its tail. Tails that are curly or doubled up aren’t as efficient when it comes to swimming.
Routinely in ICSI, a small amount of washed and prepared sperm is placed into thick viscous media that slows the sperm down so that they can be selected according to their shape, motility and trajectory.
The most “normal” looking and vigorous sperm are selected and then immobilized by squashing their tails with a glass injection needle. One these sperm are sucked into the needle tail-first ready to be injected.
Monash IVF tip: In some cases a Monash IVF embryologist will spend hours searching for the perfect sperm in a patient with a low sperm count or poor motility sperm to perform an ISCI. We stop at nothing to find the most perfect sperm.