CHROMOSOMAL STATUS OF UNI-PRONUCLEAR HUMAN ZYGOTES FOLLOWING IN-VITROFERTILIZATION AND INTRACYTOPLASMIC SPERM INJECTION

Uni-pronuclear embryos (n = 42) were analysed by fluorescence in-situ hybridization (FISH) with two to four chromosome pair-specific probes. Half of these embryos resulted from conventional insemination and hal f from intracytoplasmic sperm injection (ICSI). The majority of unipro nuclear embryos from conventional insemination were normally diploid ( 61.9%) whereas only 9.5% of unipronuclear ICSI embryos (P < 0.001) wer e diploid. In addition, a significantly higher number of uni-pronuclea r embryos from conventional insemination had a Y chromosome (10/21, 47 .6%) when compared with ICSI embryos (2/21, 9.5%) (P = 0.015). It is c oncluded that the majority of uni-pronuclear embryos following regular in-vitro fertilization are fertilized, whereas those from ICSI are pa rthenogenetically activated. The latter embryos should not be consider ed for embryo replacement.