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Clinical use of a time-lapse system and the develpoment of continuous culture media have enabled the establishment of modern incubation systems which decrease stress on the embryo. Furthermore, the use of a time-lapse system allows the accumulation of successive images of embryonic development. Various embryo morphological kinetics are beginning to be analyzed by using the collected data. A time-lapse system is useful for the accurate evaluation of implantation ability and deciding which embryos should be transferred first. Also, a time-lapse system allows the elimination of embryos which shoud not be transferred because of abnormal cleavage, or a multinucleated blastomere after the 4-cell stage.
It has been reported that oocyte dysmorphisms, such as the appearance of a cytoplasmic vacuole, granularity, and deformed shape, are strongly associated with poor embryonic development. In this study, we analyzed the dynamics of cytoplasmic dysmorphisms of oocytes and zygotes using time-lapse cinematography (TLC) that we had originally developed. Mature oocytes (n=1,601) were classified into two groups: good quality oocytes (GQO), which indicated oocytes without any defects; and poor quality oocytes (PQO), oocytes with one or more defect. Of the 1601 oocytes, 74.1% were GQO and the remaining were PQO, which were evaluated by three senior embryologists. The rate of unfertilized oocytes was significantly lower in PQO. GQO also showed a higher development rate to good quality embryos than PQO. The time required for embryonic development in GQO was significantly less than that in PQO (P<0.01). In the zygotes (n=144), 11.4% showed vacuole-like phenomenon (VLP) in the cytoplasm. The VLP appeared in the peripheral cytoplasm after extrusion of the second polar body and moved synchronously as the mPN and fPN migrated toward the central cytoplasm. The VLP size gradually increased and remained after the first cleavage. The rate of multinucleated blastomere (MNB) formation was significantly higher in embryos with VLP than in those without VLP. The appearance of VLP was closely associated with aberrant embryonic development, particularly MNB formation. Our results suggest that the dynamic morphology of the cytoplasm in oocytes and zygotes influences subsequent embryonic development and viability, suggesting that the assessment of oocyte morphology could be a useful parameter in the prediction of embryonic development.
The quality of embryos and the choice of the one with the best quality is an urgent issue in assisted reproductive technologies (ART) and the animal breeding industry. Although morphological assessments, such as Gardner criteria, are widely used, their objectivity and quantitation remain controversial. As the cellular structure and metabolism change dynamically during preimplantation development, it is desirable to monitor the whole process spatiotemporally based on multidimensional image information. We have developed a novel live-cell imaging methodology for the preimplantation embryo that enables the monitoring of the various events continuously taking place from fertilization to the blastocyst stage. One of advantage of this methodology is that we can see the effect of phenomena observed during imaging on the developmental potential to term, as cellular damage is suppressed in our system. Moreover, it allows the automatic extraction of various parameters from image data using customized algorithms developed by us. Therefore, we consider that this methodology will be a powerful tool for the quantitative analysis of the quality of embryos, and for the determination of the reasons for the attenuation of embryo quality.
At our hospital, an embryologist explains to patients the steps involved in ART and the growth situation of an embryo on day 5. However, this explanation takes a long time and patients must wait to receive it. Therefore, we conducted a survey to investigate: whether these explanations are actually useful to patients, how much of the content do patients actually understand, the level of demand for explanations, and points for improvement. We distributed a questionnaire created by our hospital for wives and for husbands to 140 couples (280 individuals) who underwent ovum pick-up or cryopreserved blastocyst transfer between January 2013 and June 2014. Multiple responses were possible, and the results were examined for each question item. A total of 147 questionnaires were recovered: 43 from husbands and 104 from wives (recovery rate: 52.5%, 147/280). Of the 106 patients who had received an explanation of ART before ovum pick-up, 100% responded that the explanation had been beneficial. Of the 106 patients who had received an explanation 5 days after ovum pick-up, 94.2% responded that the explanation had been beneficial. This indicates that many patients require an explanation from an embryologist.
Assisted hatching (AH) is becoming an established technique for the rescue of failed hatching, although its usefulness is still under debate. To investigate the usefulness of AH, we compared hatching rates, pregnancy rates, and abortion rates, depending on whether AH had been performed, in 413 patients (681 cycles) who received cryopreserved embryo transfer at our clinic from September 2011. The hatching rate was 60.6% in the AH group versus 2.9% in the non-AH group (P<0.005), a significantly higher rate in the former group. Moreover, hatching rates were 67.7% vs. 0.0% in patients aged ≤29 years, 69.2% vs. 0.0% in patients aged 30–34 years, 60.1% vs. 2.1% in patients aged 35–39 years, and 51.1% vs. 8.7% in patients aged ≥40 years, showing that the rates were significantly higher across all ages in the AH group (P<0.005). Hatching rates according to Gardner's classification were 42.5% vs. 0.0% for grade ≤2, 53.9% vs. 0.0% for grade 3, and 69.4% vs. 4.9% for grade 4, also indicating significantly higher rates in the AH group (P<0.005). There was no difference in the pregnancy or abortion rates despite the improved hatching rates from AH. These results do not prove the usefulness of AH.
Ovum pick-up (OPU) was performed for two Japanese Black breeding cows with low efficiency of embryonic collection after superovulatory treatment, and whether or not embryonic productivity was improved by the OPU was reviewed. The number of transferable embryos obtained was 2.3 per embryonic collection, 11.5 in total, from five embryo collections using conventional superovulatory treatment methods. OPU was conducted 2–3 times a month, 12 times in total in five months, for the same two cows at the fifth parity, and in vitro fertilization and culture were conducted thereafter. The number of blastocysts obtained was 19 in total, from 12 times of OPU (1.6 per OPU). Although the number of embryos produced was small per OPU, OPU made it possible to efficiently many embryos, because of multiple operations in a short period. Our results suggest that the embryo productivity of OPU is stable even in donor cows with low efficiency of embryonic productivity after superovulatory treatment.