What is ICSI?
Intracytoplasmic Sperm Injection (ICSI) consists in introducing a sperm cell directly to the inner part of an egg cell (oocyte). This procedure is carried out with the use of microneedles attached to micromanipulators. What is important and interesting is the fact that for the proper outcome of fertilization, the selected sperm cell should be living but immobile. To this aim, its tail is cut off with the use of a microneedle before it is released into the egg cell. Following the introduction of a single sperm to an egg cell, the natural process of cell division begins. Pending their transfer, embryos are incubated in the optimal conditions of the embryology laboratory…
PATIENTS’ QUESTIONS: Is ICSI/sperm immobilization safe?
Although it sounds scary, the sperm immobilization procedure in no way affects its fertilization potential or the further development of the embryo.
ICSI step-by-step
The ICSI procedure requires much attention and high concentration. It starts with the identification of patients: eggs and sperm. Then, in separate droplets, sperm cells and eggs are placed onto the same culture plate. An egg cell has a size of one-tenth of a milliliter, and a sperm cell is 100 times smaller. The whole ICSI fertilization procedure is carried out by many experienced embryologists using specialized microscope equipment.
Microscope for ICSI
Manipulator
After the plate has been placed onto the microscope stage (which is additionally heated to 37oC), in the first place a sperm with proper motility and morphology is selected. It is then immobilized and aspirated into the needle and transferred to the droplet containing the egg cell.
Sperm immobilization
PATIENTS’ QUESTIONS: Can a twin pregnancy develop if two sperm cells are introduced into the egg cell?
Unfortunately, it can’t. Placing two sperm cells in one egg cell leads to its improper fertilization; it will not result in obtaining a healthy embryo and pregnancy. Always only one, thoroughly selected sperm is released into the egg.
The egg is fertilized in the droplet which contains it. In this phase, the oocyte is assessed for maturity. The maturity is indicated by the presence of a polar body – a small, oval-shaped fragment present under the zona; its presence means that the chromosome reduction is completed and the egg is ready for fertilization. Only mature cells qualify to further ICSI procedures. The oocyte is picked up by a pipette and held through the gentle aspiration of its zona. A very important step is placing the oocyte in a proper position for fertilization. The polar body must be positioned at either 12 or 6 o’clock. Such location limits the risk of damaging the oocyte’s karyokinetic spindles during puncture.
Egg fertilization
Then the zona and cell membrane (oolemma) are punctured and the sperm is released into the egg cell. The whole procedure must be completed in quite a short time because egg cells are sensitive to light and ambient air.
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Indications for ICSI
ICSI is recommended primarily for patients qualified to the treatment with assisted reproductive techniques due to the so-called male factor. This means patients with abnormal semen parameters such as decreased concentration, decreased sperm motility in the scope of progressive movements (A and B) and patients with abnormal sperm morphology. This procedure should be considered by men with the presence of antisperm antibodies or those who underwent vasectomy. ICSI is recommended also in case of patients with failed classical in vitro fertilization (IVF) procedures, female patients with confirmed idiopathic (unexplained) infertility and reduced ovarian reserve.
Through an embryologist’s eye
The ICSI procedure is unique and crucial in the entire in vitro process. It is here that the egg fertilization occurs, it is here that life arises. The embryologist’s work involves tremendous responsibility and is often coupled with stress and expectations which cumulate in this moment. The cases of patients qualified to ICSI differ, but each of them requires personalized approach and equally big efforts. Regardless of whether the ovum pick-up results in successful retrieval of a dozen or more mature oocytes or of only a single one… When the number of eggs is low, patients are full of concerns. They wonder whether it has been worth undergoing the strain of stimulation, injections, tests, visits, treatments for such marginal effect? Embryologists know that every cell is worth attention and maximum concentration, that there is always hope. There is a group of patients where the in vitro process resulted in obtaining only one egg from which pregnancy developed and a healthy child was born. Therefore, in answer to the patient’s doubts, the embryologists say: yes, it is always worth it.