CYTOGENETIC ABNORMALITIES OF UNFERTILIZED OOCYTES GENERATED FROM IN-VITRO FERTILIZATION AND INTRACYTOPLASMIC SPERM INJECTION - A DOUBLE-BLIND-STUDY

In the present study we have assessed the cytogenetic abnormalities of unfertilized oocytes from in-vitro fertilization (IVF) and intracytop lasmic sperm injection (ICSI) programmes during a one year period (Jul y 1995 to July 1996) with the cytogenetic analysis being carried out i n a double-blind manner, A total of 88 unfertilized ICSI and 85 unfert ilized IVF oocytes were used for the study and of these 51 and 62 oocy tes, in each respective group, were suitable for analysis, The haploid y, diploidy and aneuploidy rates between ICSI (62.7, 7.8 and 5.9%) and IVF (61.3, 9.7 and 14.5%) groups were similar, A significant inter-pa tient variation in the incidence of hypohaploidy was observed within t he IVF group, Chromosomal fragmentation or breakage was observed at a similar rate in both groups of unfertilized oocytes (23.5 and 14.5% fo r ICSI and IVF respectively), A significantly higher proportion of ICS I oocytes contained sperm nuclei (27/51, 52.9%) than did IVF oocytes ( 20/62, 32.3%, P < 0.01), The distribution and state of sperm head chro matin in relation to oocyte chromosomal complement was studied in both groups, ICSI oocytes contained decondensed or swollen sperm nuclei in association with haploid oocyte chromosomes (12/27, 44.4%) or condens ed sperm heads in oocytes showing no chromosomal complements (7/27, 25 .9%), In IVF oocytes sperm heads were either arrested in the condensed state (5/20, 25%), metaphase stage (3/20, 15%) or had undergone prema ture chromosome condensation (PCC; 6/20, 30%) in association with hapl oid oocyte chromosomes, The incidence of PCC was similar in the two gr oups, A marked variation in the incidence of total chromosomal abnorma lity was observed between patients within both ICSI (0-75%) and IVF (0 -71%) groups indicating a possible similarity in oocyte quality betwee n the majority of male factor and tubal infertility patients, The type of sperm used in the two fertilization procedures showed an increased incidence of chromosomal breakage with ICSI-MESA (microepididymal spe rm aspiration) spermatozoa (4/6, 67%) compared to the ICSI-ejaculated (6/35, 17.1%; P < 0.05), ICSI-testicular biopsy (2/10, 20%) and IVF-no rmospermic (9/62, 14.5%; P < 0.01) spermatozoa. Chromosomal fragmentat ion may be associated with the degree of difficulty experienced at spe rm injection, especially with sperm retrieved from the reproductive tr act, Thus chromosomal fragmentation in ICSI may need further investiga tion using a larger sample size in order to assess the possible causat ive factors.