Evidence for a strong paternal effect on human preimplantation embryo development and blastocyst formation

Abstract

In human in vitro fertilization (I.V.F.), it was first assumed that all the embryos obtained had the same developmental potential whatever the quality of sperm. However, this has not been confirmed. We have used the coculture technique and determined the blastocyst formation rate in three groups of patients: group 1: patients with normal sperm count (> 20 x 10(6)/ml), motility (> 30%), and morphology (> 50%); group 2: patients treated by I.V.F. with frozen donor sperm; group 3: patients with severely impaired sperm quality (< 3 x 10(6) forward motile and morphologically normal spermatozoa per ml). In group 1, we found a strong correlation between cleavage rate and blastocyst formation rate (P < 0.0001) with a blastocyst formation rate comprised between 40% and 50%. This was not true for the two other groups for which the overall number of blastocysts obtained and the number of patients having at least one blastocyst were severely reduced (P < 0.0001). These data are discussed in terms of DNA quality, timing of formation of the pronuclei, and delays in cell cycles at the time of genomic activation. These observations lead to a new approach to the study of fertilizing ability of poor quality sperm. It may help in the decision as to whether couples treated for male infertility should be excluded from I.V.F. protocols.

Human pregnancies after transfer of fresh (four-to eight-cell) versus frozen-thawed blastocysts resulting from intracytoplasmic sperm injection

“…Moreover, based on results obtained from regular IVF, a negative relationship was observed between abnormal sperm parameters and embryo quality (23)(24)(25); it was found that poor sperm correspond to poor embryo formation with poor developmental potential. This was confirmed in the blastocyst formation rates in vitro (2).…”

“…However, there have been strong controversies related to using ICSI as a human therapeutic technique. The quality of the embryos obtained after ICSI could not be correlated with the previous observations gathered from regular IVF, where there was a strong negative relationship between embryo quality and abnormal sperm parameters (2)(3)(4)(5).…”

Predictive value of DNA integrity analysis in idiopathic recurrent pregnancy loss following spontaneous conception

“…Several techniques have also been developed to evaluate paternal DNA integrity independent of other sperm parameters (sperm count, morphology and motility). Abnormal spermatozoa with reduced DNA quality may compromise cleavage rate and thus affect blastocyst formation [25]. Spermatozoa carrying fragmented DNA can fertilize a mature oocyte, but activation of paternal genome further impairs embryonic development, resulting in pre and post implantation losses.…”

The effects of sperm quality on embryo development after intracytoplasmic sperm injection

“…There is published evidence that poor semen parameters result in low blastocyst formation rates after in vitro fertilization (IVF) (3,4), suggesting that sperm can influence human pre-implantation embryo development. In addition, blastocyst formation rates were shown to be lower after ICSI than after IVF (5).…”