We analyzed images of human blastocysts obtained from an in vitro culture system we have developed for time-lapse cinematography (TLC). Blastocoel collapse and re-expansion were repeated throughout the blastocyst stage because of disturbance of the trophectoderm (TE) wall. We also found an aberrant “strand phenomenon” within the blastocoel cavity in which the inner cell mass (ICM) ectopically adhered to the opposite TE wall. We also identified that this phenomenon was closely associated with the occurrence of monozygotic twin pregnancies. Monozygotic twinning increases in frequency with day-5 embryo transfers compared with day-2 or day-3 embryo transfers in human ART programs. When the blastocysts eventually escaped through the zona pellucida, we observed two types of hatching (inward and outward). Although the former was always accompanied by blastocoel collapse, this did not occur with outward hatching. We believe that the outward process without blastocoel collapse is more likely to represent the in vivo hatching pattern than the inward process. These results suggest that extended in vitro culture to the late blastocyst stage has a negative impact on human embryonic development.

Avoidance of multiple pregnancy without decrease of pregnancy rate is a challenge in ART. In 2005, we transferred an average number of 1.9 embryos, and the percentage of multiple pregnancies in double embryo transfer was 26.4% at our clinic, which was unacceptably high. In 2006, we introduced measures to avoid multiple pregnancy by decreasing the number of embryos transferred. In 2008, the average number of transferred embryos was down to 1.2 and the rate of multiple pregnancy was less than 5%. The pregnancy rate per embryo transfer was not lowered in 2008, compared with that in 2006. We found 4 factors which enabled us to reduce the multiple pregnancy rate while maintaining the pregnancy rate: blastocyst transfer instead of cleavage stage embryo transfer; frozen-thawed embryo transfer instead of fresh embryo transfer; selection of the patients who would benefit from the transferring of two embryos; and SEET (Stimulation of Endometrium Embryo Transfer) for blastocyst transfer.

Recently, we have been performing salpingoscopy concomitant to the performance of laparoscopy, and we have been constructing an evaluation scoring system using the results of salpingoscopy. From April 2008 through October 2010, 227 women who had been diagnosed with unexplained infertility underwent salpingoscopy at our clinic. With the salpingoscope, both the right and left tubal lumen were observed paying attention to following six findings: i) adhesions, ii) loss of mucosal folds, iii) rounded edges of mucosal folds, iv) debris, v) foreign bodies, and vi) abnormal vessels. One abnormal finding was given a 1-point F Score with a maximum of 12 points. We analyzed the relationship between the F scores and various clinical findings and pregnancy rates. About 51% of the patients showed an F score of 0, and the percentages of patients who showed 1, 2, 3 and 4 or more, points were 17.2, 13.2, 5.3 and 12.8%, respectively. The pregnancy rate (34.9%) of patients with a low F score (F score≤2) was significantly higher than that (14.6%) of patients with a high F score (F score ≥3, P<0.05). The patients showing a lower F score showed higher fecundity than those showing an F score of 3 or more without ART treatment.

Mammalian embryo culture is influenced by autocrine and paracrine effects and the diffusion of harmful byproducts. The physiological development of the embryo occurs in the Fallopian tube under dynamic conditions. To obtain high quality embryos in in vitro culture, dynamic culture systems (DCSs) have been developed which mimic the dynamic physiological conditions. In this review, embryo culture using DCSs in vitro and their culture results are discussed. From the culture results of DCSs that move the medium and embryos, we deduced that an increase in the diffusion rate is one of the reasons for an improvement in embryo development. Diffusion around the embryos could be investigated by monitoring pH changes in the medium during embryo culture. Application of moderate mechanical stimuli to embryos using DCSs would induce improvement in embryo development. To understand mechanosensing of mammalian embryos, mechanical stimuli and intracellular calcium concentrations in the embryos should be quantitatively evaluated. Finally, strategies to apply these insights and technologies to human embryo development are briefly discussed.

On March 11, 2011, we experienced the Tohoku-Oki earthquake and tsunami followed by the Fukushima nuclear power plant accident. As a witness of this natural disaster, I keenly realized it is essential for us to take measures under an assumption that we might face a natural event even more disastrous than the present one. We need to have our own strategy, manual, regular emergency drill, and precaution for accidents that may happen at assisted reproductive technology facilities and make changes based on our knowledge and experiences accordingly. Even at the time of a disaster, patients, staff, facilities, fresh and frozen embryos, oocytes and spermatozoa should be safely managed, while the distributed replicated storage system, patient's privacy protection and emergency transportation to other hospitals need to be carried out as best as possible. Each staff member should understand and do what they need to do quickly and flexibly according to circumstances. For future contingencies, it is crucial for all of us to secure some supplies such as drinking water, food, flashlights, radios, batteries, fuel, etc. at clinics. Staff members should ensure that they know when and how to return home and that they have adequate supplies at home.

Efforts by corporations to fulfill their social responsibilities will lead to consumers' social satisfaction and a steady rise in their stock prices. For medical institutions, the establishment of a system for the fulfillment of social responsibility would lead not only to patients' trust and satisfaction, but also to improved safety of medical care. Infertility treatment plays an important role in reversing the decline in Japan's birthrate. However, since infertility treatment, unlike other medical practices, involves birth of a new life, the results of medical services provided by infertility clinics/hospitals will have a great impact on the future society. For example, in the procedures of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), sperm and an egg are once taken out of the body, and an embryo formed from the egg is returned to the uterus. Therefore, the greatest possible care must be taken to prevent mix-up of eggs and sperm. In addition, since the process of IVF or ICSI cannot be automated with machines (in other words, IVF and ICSI are skilled manual procedures), there is a possibility that medical accidents, such as inadvertent destruction or loss of embryos, may occur. It is therefore necessary for clinics or hospitals engaged in infertility treatment to record all processes and make them transparent, and thereby become institutions patients can trust. To gain the trust of people visiting the institutions and the public at large, it would be very effective to apply the concept of corporate or organizational social responsibility to the field of infertility treatment. Medical institutions specializing in infertility treatment must establish a basic philosophy, perform infertility treatment with a sense of bioethics and social ethics, disclose all requests and complaints from patients and the countermeasures implemented in response, undergo periodic audits, know the level of satisfaction of patients and medical staff, and carry out social awareness activities. By fulfilling their social responsibility through these activities, they can improve the quality of their services.

Varicocele causes about 30% of male infertility with spermatogenetic disorder. Although surgical treatment of varicocele repair has been performed as a standard therapy, controlled trials and meta-analyses generally have not demonstrated improvement in sperm count or fertility after varicocele correction. Therefore, surgical ligation of the varicocele should not be routinely conducted for infertile males with varicocele, except for younger infertile men with a clinically apparent varicocele. Surgical repair is superior to artificial reproductive techniques in cost effectiveness. Microscopic subinguinal ligation of a varicocele with artery preservation is recommended among the treatment methods because of its lower rates of adverse events and recurrence of varicocele.

Numerous genes derived from retroviruses are known to be expressed in mammalian genital tracts, particularly the uterus and placenta. Syncytin 1 and 2 in humans and syncytin A and B in mice are membrane proteins originating from envelope genes of endogenous retroviruses (ERVs), and are involved in the fusion of trophoblast cells, resulting in multinucleated syncytiotrophoblast formation. Recent studies have shown that syncytin-like putative fusogenic proteins are expressed in the placenta of rabbits and possibly cows. Today, it is believed that ERVs play an important role in trophoblast development and placental formation. However, the syncytin genes so far characterized have been endogenized to the host genome only within the past 12–40 million years, more recently than the acquisition of mammalian placenta, estimated to be more than 100 million years ago. This time difference has not been explained. In this review, we present these ERVs and related but distinct fusogenic and non-fusogenic genes, and discuss their potential roles in placental development. We then propose our “baton pass” hypothesis, in which a new gene such as one of the ERVs replaced a pre-existing gene and acquired the role that gene had played, accounting for time differences between ERVs endogenization and placental evolution.

We investigated how the visibility and position of the mitotic spindle which had undergone affects embryogenesis. The subjects were 830 oocytes at metaphase II intracytoplasmic sperm injection (ICSI). When the mitotic spindle was visible, oocytes were classified into the following groups according to its position: Group A, directly beneath the polar body; Group B, at 0°< to ≤45° clockwise from the polar body; Group C, at 45°< to ≤90°; Group D, 90°< to ≤135°; and Group E, 135°< to ≤180°. When invisible, oocytes were classified into Group F The percentage of Groups A to F were 57.4%, 38.5%, 3.5%, 0.5%, 0.1%, and 27.9%, respectively. The fertilization rate, the good embryogenesis rate, the blastocyst formation rate, and the good blastocyst formation rate of the visible oocytes (Groups A to E) were 70.6%, 48.3%, 41.5%, and 5.2%, respectively, and those of the invisible oocytes (Group F) were 65.9%, 47.7%, 29.5%, and 4.2%, respectively. The fertilization rate and the blastocyst formation rate tended to be higher for the visible oocytes. We confirmed that visualization of the mitotic spindle after ICSI is a meaningful method.