The developmental competence in vitro of immature oocytes from mouse early preantral follicles in a simplified culture was investigated. The follicles ware obtained from 4-10 weeks and 14 days old mice, respectively. On day 12 of culture, most of cultured follicles ware survived (100% vs 97%) in this culture system. The granulosa cell outgrowth was observed in all of surviving follicles. The oocytes grown in vitro ware leaded to GVBD (84% vs 96%), and 44% of them reached Metaphase II, respectively. This results show that this culture system is valid in not only preantaral follicles from prepuberal mouse but also that of postpuberal periods.

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The cumulative incidence of type 2 in a diabetic model (SDT) rat has been shown to be much higher in males than in females. We examined the effect of sex hormones on diabetic features, body weight, plasma glucose concentration and pancreas histopathology, in castrated females and castrated females followed by injection of estrogen until 26 weeks of age. The body weights in castrated females were significantly greater than sham-operated females and castrated females with estrogen injection. On the other hand, they were lower in castrated females with estrogen injection than in castrated females and sham-operated females. Castrated females with estrogen injection had plasma glucose concentrations that were significantly lower than castrated females and sham-operated females. Histopathologically, inflammatory cell infiltration, proliferation of fibroblasts and hemosiderin deposition were observed in and around pancreatic islets in sham operated females and they were aggravated in castrated females. In castrated females with estrogen injection, these changes were seldom observed. These results suggest that female estrogen play a preventive role in diabetic pathogenesis in female SDT rats.

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The advantages of blastocyst transfer in mid-good responders include a reduction in multiple pregnancies due to single good-quality blastocyst transfer and an elevation of implantation and ongoing pregnancy rates due to establishment of the vitrification method. However, evidence is lacking as to whether blastocyst culture is effective in poor responders. In fact, few centers have adopted blastocyst transfer for all patients. Blastocyst development rate is around 50-60%. Several kinds of commercial sequential media are currently available and almost all Assisted Reproductive Technology (ART) units use these for treatment of patients. However, the period in which these media can be used is limited to 26-70 days according to the instructions provided by manufacturers. The half-life of pyruvate and antibiotics is supposedly short, and vitamins and hormones are unstable. Ideally, centers would make and use their own media within 72 h. In the near future, optimal ovarian stimulation, culture conditions, embryo transfer and luteal support should enable the possibility of providing healthy pregnancy following single blastocyst transfer in almost all patients.

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