Pronuclear Fading Research Articles

Relationships between sperm DNA fragmentation, age of donors and patients and children with psychic disorders

OBJECTIVE: Some authors describe similar and high fertilization and pregnancy rates in non-obstructive azoospermia (NOA) patients whereas others report lower outcomes in NOA than in obstructive azoospermia (OA) patients. Sperm DNA damage is associated with reduced fertilization rates, embryo quality and pregnancy rates and higher rates of spontaneous miscarriage and childhood disease. Meanwhile, mouse zygotes respond to spermDNA damage through a non-apoptoticmechanism that acts by slowing paternal DNA replication and embryonic development. In this study, we compared the early development of embryos fertilized with NOA and OA spermatozoa by using time-lapse monitoring system. DESIGN: This is a retrospective study. MATERIALS AND METHODS: Six oocytes with ICSI using testicular spermatozoa from NOA and 35 oocytes with OA from 2013 to 2014 were used. The exact times for each embryo division and developmental parameters were calculated in hours after ICSI. Time-lapse images of each embryo were retrospectively analyzed by PrimoVision software. The developmental events observed in each embryo were at the time of the visibility of two pronuclei (2PN), syngamy, two cells and four cells. These parameters were compared between the NOA group and the OA group. RESULTS: The time of the visibility of 2PN in the NOA group (9.5 1.4 hours) was significantly earlier than that in the OA group (12.1 2.3 hours). However, the time from the visibility of 2PN to the syngamy in the NOA group (13.2 3.4 hours) was significantly longer than that in the OA group (10.6 2.7 hours). The time between the syngamy and the two cells in the NOA group (12.2 1.3 hours) was comparable with that in the OA group (16.6 10.2 hours). The time from the two cells to the four cells in the NOA group (13.5 3.5 hours) was also comparable with that in the OA group (10.0 4.2 hours). CONCLUSION: The time from the visibility of 2PN to the pronuclear fading (syngamy) after ICSI with testicular spermatozoa from NOAwas prolonged compared to that after ICSI with testicular spermatozoa from OA.

The human first cell cycle: impact on implantation

The morphology of fertilization events has been related to successful implantation by subjective criteria (pronuclei score, pronuclei symmetry and position). This work first described these events by time-lapse technology and then compared the timings of fertilization events (second polar body extrusion, first and second pronuclei appearance, abuttal and fading) in implanted versus nonimplanted embryos in a 2-year cohort retrospective study. A total of 1448 transferred embryos from 842 patients undergoing intracytoplasmic sperm injection with oocyte donation were monitored, 212 embryos from treatments where the number of gestational sacs matched the number of transferred embryos and 687 embryos from treatments no biochemical pregnancy was achieved. The timings at which second polar body extrusion (3.3–10.6h), pronuclear fading (22.2–25.9h) and length of S-phase (5.7–13.8h) occurred were linked successfully to embryo implantation. The other parameters were apparently not related, as determined by image acquisition and time-lapse analysis.The morphology of fertilization events has been related to successful implantation by subjective criteria (pronuclei (PN) score, PN symmetry and PN position). Now we describe for the first time the same events by time-lapse technology and also compare timings of the fertilization events in implanted versus nonimplanted embryos in a 2-year cohort retrospective study, in which 1448 individual embryos from 842 patients undergoing ICSI with oocyte donation were monitored. Only embryos from treatments where the number of gestational sacs matched the number of transferred embryos (n=212) and embryos from treatments where no biochemical pregnancy was achieved (n=687) were included in the study (Known Implantation Data). The chronological pattern of fertilization events as well as other morphological features were recorded. The means of the timings of the pronuclei events were analysed in both groups. The timing of PN disappearance could be linked to successful embryo implantation, whilst the other parameters analysed were apparently not related, as determined by image acquisition and time-lapse analysis. However, further studies are needed to successfully apply these findings for embryo selection.

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.A key step in assisted reproduction is the assessment of oocyte and embryo viability to determine the embryo(s) most likely to implant. Current embryo assessment strategies in clinical settings largely rely on embryo morphology and cleavage rates, and although these systems have been successful in improving pregnancy rates, their precision is far from ideal as they are based on visual information. In contrast, automated image analysis may add objectivity to the process of embryo selection and consequently, lead to an improvement in the implantation rates. Timing of zygote development can be influenced by the method of fertilization or by in-vitro culture conditions, so it has been suggested that the fertilization procedure influences the length of time elapsed between fertilization and the first cleavage. In this report, we show the results from using a time-lapse monitoring system to determine the timing of key events during embryo development both in IVF and ICSI. Due to the different intrinsic characteristics of the classic IVF and ICSI techniques, the selection of a critical time point is essential so as to maximize the differences between the two methods. For that reason, we searched for evidence in the data obtained from the image analysis for a link connecting embryo cleavage and the fertilization technique and also to find whether the kinetic of development derived from classic IVF or ICSI is also related to a predicted higher implantation.