Consequences of polyspermy in man

Abstract

Polyspermy occurs with a frequency of about 12% under some hormonal regimens currently being used for in vitro fertilization and embryo transfer. Oocytes with three pronuclei usually show normal cleavage and are morphologically indistinguishable from embryos produced by normal fertilization. Chromosome studies and DNA measurements on dispermic embryos show that about one-half are triploid, the others having either a normal diploid chromosome complement or a severely depleted chromosome complement. The evidence suggests that these errors must arise at the first mitotic division of the oocyte. Aberrant spindle formation is implicated.

Altered cleavage patterns in human tripronuclear embryos and their association to fertilization method: A time-lapse study

“…The vast majority of triploid embryos can be recognized at the zygotic stage by the appearance of 3 pronuclei (PN) instead of the normal 2. Otherwise, 3PN and 2PN embryos have the same morphological appearance [8]. Diandric triploids are estimated to account for approximately 80 % of 3PN IVF inseminated embryos [9] and over 80 % of these are due to dispermy [3].…”

“…Previous analyses of the cleavage patterns in 3PN IVF and ICSI embryos have focused on the chromosomal contents rather than the dynamics and timing of various cell cycle events [2,8,[10][11][12][13][14]. An abnormal 1st cleavage in 3PN embryos has been described by observing 10 cases [15].…”

Fertilization and early embryology: The chromosomal complements of multipronuclear human zygotes resulting from intracytoplasmic sperm injection

“…Cytogenetic evidence has shown that zygotes having three pronuclei usually arise through dispermic fertilization and at the first cleavage contain one maternal and two paternal genomes (Rudak et al, 1984;Angell et al, 1986). However, the main advantage in analysing the first cleavage division of tripronuclear zygotes is that the chromosomes of gametes 2496 remain in discrete haploid clusters.…”

Embryo developmental potential of microsurgically corrected human three-pronuclear zygotes

“…This disordered distribution of chromosomes has been observed by FISH. Angell et al [1986] reported that about one third of zygotes had triploid chromosome, the others had normal diploid chromosome or severe chromosome deletions in 3PN zygotes. Kola et al [1987] and Pieters et al [1992] described that the first cleavage into 3 cells occurred in 62% of 3PN zygotes which had severe chromosome abnormalities, but was not triploid.…”