Advanced maternal age at childbirth is a risk factor for the generation of trisomies such as Down syndrome because of the high frequency of non-disjunction at maternal meiosis 1. Thus, it is predicted that increased childbearing age is also relevant to the generation of maternal uniparental disomies caused by trisomy rescue or gamete complementation with a disomic oocyte produced through non-disjunction at maternal meiosis 1. Here, we report our molecular genetic data for 117 patients with Prader-Willi syndrome. The results indicate that advanced maternal age at childbirth is a predisposing factor for the development of maternal uniparental disomy 15 because of increased meiosis 1 errors. This notion is applicable to other maternal uniparental disomies as well, and provides useful insight into the occurrence of imprinting disorders after artificial reproductive technologies(ART). In particular, it is recommended to perform maternal age-matched comparison for the evaluation of the potential influence of ART on the development of maternal upd.

抄録全体を表示

Many researchers are focusing on epigenetic regulation in the placenta. Because the proper development and function of the placenta are crucial for the normal healthy growth and survival of the developing fetus, the study of epigenetic alterations is providing critical insights into the biology of fetal development and the pathogenesis of complications in pregnancy. One epigenetic alteration is genomic imprinting. Alleles from both the father and mother are necessary for normal human and placental development. For example, the paternally expressed IGF2 gene and maternally expressed H19 gene are located in 11p15.5 and they are coordinately regulated by differentially methylated regions (DMRs). The main phenotype of Silver-Russell syndrome is severe fetal growth retardation (FGR) that is caused by a reduction in IGF2 transcription as a result of a loss of methylation at the H19 DMR. Hypermethylation at the H19 DMR is found in 30% of cases of Beckwith-Wiedemann syndrome and the overgrowth phenotype. The other main mechanism is a promoter DNA methylation. Hypomethylation of a promoter of the SERPINA3 gene in the placenta is associated with FGR and preeclampsia. These clues to the epigenetic phenomena involved in the processes of human development and disease in pregnancy have been found in recent years.

抄録全体を表示

Maternal fertility decreases with aging, possibly owing to qualitative changes in the egg itself and the egg-housing condition of the female reproductive tract. Since sperm first interact with the egg-coating structures, age-dependent alterations of egg-coating structures may be related to reduced fertility in aged female mammals. Quantitative genetic and biochemical studies of specimens prepared from aged mammals have revealed altered expression patterns of antioxidant- and apoptosis-related proteins in cumulus cells, and a substantial decrease in the amount of ZP-constituent glycoproteins. Histochemical studies have demonstrated an increase in the number of apoptotic cumulus cells and significant alteration in the appearance of ZP with irregular plaques in aged specimens. Biophysical studies have shown that both susceptibility to digestion with protease and mechanical stiffness are reduced in the ZP aged in vitro. We recently characterized a novel suppressive factor of fertilization, dicalcin, in the cumulus-oocyte complex. The expression level of dicalcin in the cultured normal human fibroblasts increases with the passage of time, which implies an age-dependent increase in its expression in the normal female reproductive tract. The potential increase in dicalcin expression with aging would represent a qualitative change of the egg-coating structure, augment its inhibitory role on fertilization, thereby causing decreased fertility in aged female mammals.

抄録全体を表示

Women in Japan and elsewhere are increasingly delaying childbearing. The percentage of Japanese women giving birth to their first child at the age of 30 and above has increased from 28.9% in 1980 to 58.9% in 2009. As a result, women seeking to conceive one or more children increasingly do so when the effects of reproductive aging first become noticeable. Female fertility begins to decrease after 30 years of age, falls markedly after the age of 35 in association with an increased risk of complications during pregnancy and of chromosomal abnormalities in the offspring, and most women become infertile after the age of 40. In parallel, the number of assisted reproductive technology (ART) treatment cycles in Japan is steadily increasing, from 37,455 in 1997 to 190,613 in 2008, according to a survey by the Japan Society of Obstetrics and Gynecology. Because of the high emotional and social toll of infertility on couples and the demographic consequences of a decrease in fecundity, it is imperative to better understand the biology of reproductive aging. Here we review current knowledge about the decline of female fertility during aging and discuss the implications for infertility treatments.

抄録全体を表示

In the present study, we investigated the effects of a specific Rho kinase (ROCK) inhibitor, Y-27632, on germinal vesicle breakdown (GVBD), changes of cytoskeletal organization, and the resumption of porcine oocyte maturation after its removal. In Experiment 1, cumulus-oocyte complexes (COCs) cultured in medium containing Y-27632 for 24 h showed GVBD of 98, 88, 84, and 4% (P<0.01) of the oocytes treated with 0, 1, 10, and 100 μM of the drug, respectively. In addition, Y-27632 treatment from 24 to 44 h of incubation significantly inhibited maturation of the oocytes. The metaphase II (MII) rates were 84, 78, 65, and 10% (P<0.01) for the corresponding groups, and 0, 2, 8, and 45% of the oocytes failed to show emission of the first polar body (PB1). In Experiment 2, resumption of meiotic maturation was examined after removal of Y-27632. COCs incubated with Y-27632 for 18 h and then cultured in Y-27632-free medium for an additional 44 h showed a significantly lower MII rate (86 vs. 33%, P<0.01). After the addition of Y-27632, cortical microfilaments of the oocytes decreased in density to approximately 40% of that of the controls. The present results suggest that Y-27632 inhibits GVBD and emission of PB1 in porcine oocytes and that ROCK inhibition for 18 h after the start of maturation incubation may be detrimental to and exert an irreversible effect on the progression of meiosis.

抄録全体を表示

Bovine intracytoplasmic sperm injection (ICSI) is a useful technique in the production of calves. Generally, oocytes matured in vitro are used for bovine ICSI, but the developmental competence is lower than that of oocytes matured in vivo. The objective of this study was to evaluate the effect of dibutyryl cAMP (dbcAMP) during in vitro maturation (IVM) on meiotic maturation, sperm aster formation, and blastocyst development after ICSI. Cumulus-oocyte complexes were cultured in TCM199 supplemented with 100 μM dbcAMP in the presence or absence of follicle-stimulating hormone (FSH) and epidermal growth factor (EGF) in the following treatment four groups: an untreated control, dbcAMP, FSH/EGF, and FSH/EGF/dbcAMP. The percentage of MII oocytes at 21 h did not differ among the four groups (66.7–73.9%). The percentages of sperm aster formation in the FSH/EGF and FSH/EGF/dbcAMP groups (87.1% and 85.7%, respectively) and the diameter of sperm asters in the FSH/EGF/dbcAMP group (81.6 ± 2.7 μm) were significantly greater than those in the other groups. The blastocyst rate in the FSH/EGF/dbcAMP group (42.7%) was significantly greater those that in the other groups. Thus, adding dbcAMP together with FSH and EGF to IVM medium stimulated the sperm aster formation in bovine oocytes and increased the blastocyst rate after ICSI.

抄録全体を表示

[Objective] To present a case of pregnancy achieved by oocyte donation abroad to a woman with 47,XXX and premature ovarian failure (POF). [Patient(s)] A 39-year-old woman, gravida 0, para 0, with 47,XXX, POF and hypertension, achieved pregnancy by donation of oocytes abroad, and consulted us for pregnancy management. Dichorionic diamniotic twin fetuses were observed by ultrasonography, and gestational diabetes mellitus (GDM) occurred at 12 weeks of gestation. One of the twins was diagnosed with intrauterine growth restriction (IUGR) at 24 weeks of gestation. Uterine contraction was frequently observed at 28 weeks of gestation. Brain sparing effect was seen in the IUGR fetus at 30 weeks of gestation. The IUGR fetus presented a non-reassuring fetal status (NRFS) at 32 weeks of gestation, therefore twins were delivered by Caesarean section. [Results] Neonate 1 weighed 1,754 g with an Apgar score of 9/10 (1/5 minutes). Neonate 2 weighed 950 g with an Apgar score of 7/8. Both did well. While GDM improved in three weeks, the patient’s hypertension persisted after delivery. [Conclusion] This kind of case will increase in Japan due to the emergence of middlemen for oocyte donations. To prepare for them, it is necessary to further investigate mechanisms of complications in pregnancies achieved with donated oocytes.

抄録全体を表示

The effect of intraperitoneal administration of desialylated erythropoietin (asialo EPO) on the follicular reserve of cryopreserved canine ovarian tissues was examined using non obese diabetic-severe combined immunodeficient (NOD-SCID) mice was examined. Vitrified-warmed canine ovarian tissues were placed under the dorsal skin of mice, and were then treated with saline or 400 or 4,000 U/kg/day of asialo EPO by intraperitoneal injection from one day before transplantation for 5 days. Transplanted tissues were removed and subjected to a histological examination 4 weeks after the transplantation. Without asialo EPO treatment, the mean number of primordial follicles in the cryopreserved ovarian tissues had decreased from 4.3/mm² to 0.2/mm² at 4 weeks after xenotransplantation. However, higher numbers of follicles were observed when recipient mice were treated with asialo EPO. The average number of primordial follicles per square millimetre of ovarian section was 0.2 in the saline group and 1.1 in the 400 U/kg/day of asialo EPO at 4 weeks after transplantation. These results indicate that the systemic administration of asialo EPO could be effectively used to enhance the survival of the follicles of transplanted cryopreserved canine ovaries.

抄録全体を表示