Premature Chromosome Condensation Of The Sperm And Oocyte Nucleus In Faild Fertilized Oocytes After In Vitro Fertilization Procedures



Introduction: The incidence of sperm and oocyte premature chromosome condensation (PCC) in the failed fertilized oocytes that were taken after routine in viro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) programs were investigated.
Materials and methods: In this study, 364 air-dried preparations of failed fertilized oocytes after either IVF or OCSI procedures were analyzed. The zona pellucida of the oocyte was removed by thyrod\rquote s acid. The oocytes then were subjected to a hypotonic solution for 15-20 minute. This solution consisted of sodium chloride. disTilled water and sodium citrate, which resulted in the swelling of the cell. The swelled oocytes were fixed sequentially in three different fixatives then they were stained in 10% Giemsa and examined with light microscope an x1000.
Results: A high frequency of intact sperm head were noticed in the failed fertilized oocytes. The number of intact sperm head was higher in ICSI procedure than IVF (46.5% versus 30.5%), however the difference was statistically not significant. On the Other hand, PCC of the sperm were significantly in ICSI higher than IVF (16.1% gersus 8.8%, P< 0.05). Oecondensed chromatins and degenerated) chromosome were also seen in some oocytes.
Conclusions: An abnormal chromatin decondensation or PCC of sperm head and oocyte nucleus occurs in the failed fertilized oocytes after IVF procedure. Several factors can be associated with the above abnormalities such as the failure of oocyte activation or an immature retrieval of oocytes. The presence of an intact sperm head may indicate that the sperm nucleus is not accessible to ooplasmic factors, where the sperm nucleus should interact with chromosome condensing factors. This may result in the induction of PCC because of the non-activated oocyte has remained in metaphase II.