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Purpose Assisted reproductive technology (ART) is a widely applied fertility treatment. However, the developmental competence of aged oocytes from women of a late reproductive age is seriously reduced and the aged oocytes often fail in fertilization even when ART is used. To resolve this problem, we examined usefulness of a new method “the metaphase II spindle transfer (MESI)” as ART using mouse oocytes. Methods This work was composed of two experiments. First, 24 hours after collection, embryos from oocytes (1‐day‐old oocytes, called postovulatory‐aged oocytes), were observed, after intracytoplasmic sperm injection (ICSI), and it was found that they were not able to reach the blastocyst stage. Next, the metaphase II chromosome‐spindle complexes from 1‐day‐old oocytes were injected into cytoplasts from oocytes just collected, using piezo pulses to generate reconstructed oocytes. This procedure was named metaphase II spindle injection (MESI). Results After ICSI, embryos from the reconstructed oocytes (32/105), which contained the genes of 1‐day‐old oocytes, were able to develop into the blastocyst stage. The fragmentation rate after ICSI was 28.6%. Thus, the developmental competence of 1‐day‐old oocytes was improved by MESI. Conclusions The MESI method has the potential to improve the success rate of infertility treatments for women of a late reproductive age., The metaphase II chromosome‐spindle complexes from 1‐day‐old oocytes (postovulatory‐aged oocytes 24 hours after collection) were injected into cytoplasts from freshly collected oocytes using piezo pulses to generate reconstructed oocytes (MESI). After ICSI, the embryos from reconstructed oocytes (32/105) could develop into the blastocyst stage. However, the developmental competence of 1‐day‐old oocytes was improved by MESI.

Purpose Previous studies have reported different methods of estrogen administration during endometrial preparation for frozen‐thawed embryo transfer (FET). This study aimed to investigate a beneficial regimen of transdermal estrogen administration for FET. Methods We investigated the reproductive and obstetric outcomes of FET by comparing the increasing dose (ID) group that mimics changes in serum estradiol during the menstrual cycle and the constant dose (CD) group. Transdermal patches were used for estrogen administration in both groups. In our hospital, we targeted 315 cycles of the ID group in which FET was performed in 2017 and 324 cycles of the CD group in which FET was performed in 2018. In all cases, single embryo transfer was performed. Results All were singleton pregnancies. There was no difference in clinical pregnancy rate (28.9% vs 28.2%, P =.837) and live birth rate (17.3% vs 21.4%, P =.201) between the ID and CD groups. Spontaneous abortion rate was significantly lower in the CD group than in the ID group (37.2% vs 23.0%, P =.041). There was no difference in obstetrical outcomes. Conclusions It was considered that the simple CD regimen may be more beneficial than the complicated ID regimen.

Background and Aims: Nuclear proteins in mature mammalian spermatozoa nuclei are oxidized to form numerous disulfide bonds. Reduced glutathione (GSH) in the oocyte has been linked to spermatozoan nuclear decondensation after fertilization. In this study, we analyzed whether GSH reduced protamines in sperm nuclei in vitro, and examined the zona‐binding ability of treated nuclei.

In eukaryotic cells, mitochondria are the major site of ATP production, which is achieved through the electron‐transport chain and oxidative phosphorylation, according to the energy demand. Mitochondria contain their own genome (mitochondrial DNA, mtDNA) on which a limited number of genes are encoded. In the human sperm, mitochondria helically wrap the midpiece of the tail and supply the energy for the driving force of motility. While various mutations in mtDNA in somatic cells are found to be associated with a wide spectrum of diseases, it is also reported that the abnormal mtDNA causes astenozoospermia and male infertility. At fertilization, the paternal mitochondria and mtDNA are rapidly degraded early in embryogenesis, thus, only maternal mtDNA is transmitted to the descendant. We briefly review here the basic characteristics of mtDNA and its maternal transmission during fertilization, as well as male infertility. (Reprod Med Biol 2002; 1: 41–47)

Background, Aims and Methods Clomiphene citrate (CC) has been widely used for induction of ovulation; however, despite the high rate of ovulation, the pregnancy rate is only 30%. The anti-estrogenic effect of CC on the endometrium is one explanation for this finding. It is well known that repeated administration of CC enhances its anti-estrogenic effect. To overcome this adverse affect, a number of techniques have been used. One technique is the early administration of CC, in an attempt to decrease the anti-estrogenic effects of CC on the endometrium. The aim of the present study was to retrospectively evaluate if repeated administration of CC at varying times may affect the endometrium during preovulatory period; pregnancy rates were compiled for patients with unexplained infertility undergoing intrauterine insemination (IUI). The patients were divided into four groups based on the number of repeat administrations and the time of CC administration.

In the summer of 2002, standard guidelines for the application of assisted reproductive technology were reported by a research group of the Ministry of Health, Labor and Welfare. The present study aimed to examine the relationship between the number of cycles of artificial insemination and the cumulative pregnancy rates according to the cause of infertility. Patients who experienced their first cycle of artificial insemination during the period of January 1999-December 2002 were included in the study and were divided into a male factor infertility group and an idiopathic infertility group. Cumulative pregnancy rates resulting from artificial insemination with the husband’s semen were calculated by the life-table approach. During the study period, 139 couples entered the assisted reproduction program and underwent 581 cycles. Significant differences were observed in cumulative pregnancy rates between the two groups. It is recommended that couples with male factor infertility and who fail to conceive within six or seven cycles of intrauterine insemination, consider a modification of treatment strategy such asin vitro fertilization, because cumulative pregnancy rates of this group were reached at a plateau within six or seven cycles. In contrast, patients with idiopathic infertility, the cumulative pregnancy rates appeared to increase constantly with each subsequent cycle. It is important to consider modifications of treatment strategy in the light of the cause of infertility.

Background and Aims Nuclear proteins in mature mammalian spermatozoa nuclei are oxidized to form numerous disulfide bonds. Reduced glutathione (GSH) in the oocyte has been linked to spermatozoan nuclear decondensation after fertilization. In this study, we analyzed whether GSH reduced protamines in sperm nuclei in vitro, and examined the zona-binding ability of treated nuclei.

In eukaryotic cells, mitochondria are the major site of ATP production, which is achieved through the electron-transport chain and oxidative phosphorylation, according to the energy demand. Mitochondria contain their own genome (mitochondrial DNA, mtDNA) on which a limited number of genes are encoded. In the human sperm, mitochondria helically wrap the midpiece of the tail and supply the energy for the driving force of motility While various mutations in mtDNA in somatic cells are found to be associated with a wide spectrum of diseases, it is also reported that the abnormal mtDNA causes astenozoospermia and male infertility. At fertilization, the paternal mitochondria and mtDNA are rapidly degraded early in embryogenesis, thus, only maternal mtDNA is transmitted to the descendant. We briefly review here the basic characteristics of mtDNA and its maternal transmission during fertilization, as well as male infertility.