Oocyte insemination techniques are related to alterations of embryo developmental timing in an oocyte donation model

Because of the different intrinsic characteristics of the classic IVF and intracytoplasmic sperm injection (ICSI) techniques, the timing of zygote development can be influenced by the method of fertilization. However, there is no information about the relevance of the insemination procedure on embryo-quality parameters as measured through their developmental dynamics. The aim of this work was to determine if the insemination technique, IVF or ICSI, influences embryo developmental kinetics by examining 1203 embryos from 178 couples undergoing oocyte donation with IVF or ICSI. Using time-lapse information, this work calculated several developmental kinetic variables, from pronuclear fading (PNF) to expanded blastocyst, and also the proportion of optimal embryos in a best time range with a predicted higher implantation potential. Embryo development after ICSI was slightly faster than after IVF; however, when PNF, rather than time of insemination, was established as t0, the differences between the two procedures disappeared. The percentage of optimal embryos showed a trend towards higher values in IVF-derived embryos; however, the difference was not statistically significant. With these results and through the time-lapse monitoring system, it is concluded that it is the fertilization method which determines embryo developmental kinetics if insemination time is used as the starting point. (C) 2013, Reproductive Healthcare Ltd. Published by Elsevier Ltd.