Chromosomal analysis of "failed-fertilized" human oocytes resulting from in-vitro fertilization and intracytoplasmic sperm injection

Abstract

To evaluate the incidence of chromosomal abnormalities in "failed-fertilized" oocytes derived from in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) procedure, a cytogenetic analysis was performed on 164 IVF and 64 ICSI oocytes. One hundred and eleven (67.7%) of the IVF and 56 (87.5%) of the ICSI oocytes were successfully karyotyped. Of 111 IVF oocytes, 73 (65.8%) exhibited normal haploid and 38 (34.2%) were abnormal. The abnormalities included 25 aneuploid (22.5%) (7 hyperhaploid and 18 hypohaploid), 11 diploid (9.9%) and 2 structural anomalies (1.8%). Of 56 ICSI oocytes, 52 (92.8%) were normal haploid and only 4 (7.2%) were aneuploid, with 2 hyperhaploid and 2 hypohaploid. The sperm nuclei were observed in 43 IVF oocytes (38.7%), composed of 38 (34.2%) premature chromosome condensation (PCC) and 5 (4.5%) decondensed sperm heads. Evidence of successful sperm delivery was found in all 56 ICSI oocytes ; 25.0 per cent (14/56) showed PCC, 17.9 per cent (10/56) showed decondensed sperm heads, and 57.1 per cent (32/56) showed intact sperm heads. This study suggested that about one-third of unfertilized oocytes exhibited chromosomal abnormalities. The difference of aneuploidy between IVF and ICSI oocytes needs further studies analysing a larger number of oocytes.