TETRAPLOIDY AND PARTIAL ENDOREDUPLICATION IN A TRIPRONUCLEAR ZYGOTE OBTAINED AFTER INTRACYTOPLASMIC SPERM INJECTION

Objective: To describe a peculiar combination of cytogenetic abnormali ties in a tripronuclear zygote obtained after intracytoplasmic sperm i njection (ICSI).Design: Case report. Setting: A university hospital. P atient(s): A couple with a 4-year history of primary infertility. Intr acytoplasmic sperm injection was performed because of male factor infe rtility (oligoteratozoospermia). Intervention(s): Ultrasound-guided tr ansvaginal follicular aspiration. Main Outcome Measure(s): Chromosomal karyotype of a tripronuclear one-cell zygote. Result(s): Unexpectedly , a tetraploid [92,XXYY,end3,-18,-18,end18] chromosome complement was found, indicating injection of a diploid spermatozoon carrying two Y c hromosomes. The parental origin of the other abnormalities could not b e determined. The missing chromosomes may be attributed either to a hy podiploid [44,YY,-18,-18] sperm cell or to a hypohaploid [22,X,-18] oo cyte. The exact tetraploid count was restored by endoreduplication of two chromosomes. This event could have occurred in one and the same or in two different pronuclei. Conclusion(s): Cytogenetic analysis of mu ltipronuclear zygotes appears useful for assessing the incidence of ch romosomal abnormalities at the earliest stage of conception. In additi on to other methods, it also may contribute to evaluation of the trans mission of aberrations by spermatozoa from infertile men. (C) 1998 by American Society for Reproductive Medicine.