PICSI (Petri Dish ICSI, Petri dish for ICSI) is an auxiliary method for sperm collection for ICSI. The peculiarity of the dish is that it is covered with a thin layer of hyaluronic acid. The spermatozoa are placed in this dish and those who are contacted with hyaluronic acid are physiologically normal. The essence of the method lies in the ability of sperm to attach to hyaluronate.
Hyaluronic acid is the main component of the cumulus complex that surrounds the egg cell. Due to specific receptors on the sperm’s head, mature sperm with low DNA fragmentation and a normal level of aneuploidy, can bind to hyaluronic acid. Thus, PISCI provides a quick assessment of the degree of maturity and structural integrity of the sperm, and also to determine the correlation between the morphology and the ability to fertilize the egg.
This method is based directly on the natural ability of the spermatozoa to bind to the component of micro surroundings of the egg cell – hyaluronic acid.
Hyaluronic acid is heteropolysaccharide, which is part of the extracellular matrix of cumulus cells surrounding the oocyte. In order for the sperm to penetrate and fertilize the egg cell, naturally, it should communicate with the hyaluronic acid via the membrane receptors. Only mature, biochemically competent sperm cells have this property. Scientific studies have shown that sperm cells which are associated with hyaluronic acid in vitro have better morphology, statistically less chromosomal anomalies (mutations, aneuploidy) and a higher index of DNA integrity.
So, the purpose of selection of spermatozoa by the method of PISCI is the selection of the mature and high-quality sperm, since it is precisely poor sperm quality repeatedly becoming the cause of unsuccessful attempts of IVF. It is important to understand that the conditions which are used for such a method of spermatozoa selection will be the most similar to the natural reproductive process. When embryologists choose a sperm cell with only visual valuation, such defects as chromosomal mutations or DNA damage of sperm cells, or presence of immature sperm cells can not be detected. Therefore, if there is a suspicion of chromosomal aneuploidy or a high degree of DNA fragmentation is established, the PICSI method is recommended.
During ICSI, spermatozoa are selected for injection based on their form (morphology) and mobility. However, this is a visual approach, and it does not necessarily reflect the function of the sperm and its ability to fertilize the egg. PICSI is a kind of ICSI that provides functional testing for sperm to help the embryologist.
PICSI can be especially useful for men with:
♦ previous unsuccessful IVF attempts;
♦ weak development of the embryo in the previous attempts of ART;
♦ broken morphology of spermatozoa;
♦ impaired sperm motility;
♦ sperm obtained by the TESA or MESA method;
♦ sperm that was cryopreserved;
♦ high degree of DNA fragmentation of spermatozoa.