The present study revealed that mitochondria translocated in the cell cycle and suggested that there is a close relationship between mitochondrial translocation and developmental arrest.

The immunohistochemical distribution of superoxide dismutase (SOD) was examined in the human endometrium throughout the menstrual cycle. Surface and glandular epithelia showed positive staining throughout the menstrual cycle except just prior to the menstruation.Staining activity was more intense in the cytoplasm than that in the nucleus. Specific immunostaining of SOD was demonstrated in sub-and supranuclear vacuoles of glandular epithelia, and intraglandular substances during the early and mid secretory phases; i.e., the preand peri-implantation periods. Meanwhile, stromal cells showed weaker staining activity than surface and glandular epithelia throughout the menstrual cycle until the 22th day. Once the predecidual change occurred in stromal cells on the 23th day, predecidual cells came to show intensive staining. However, specific staining was shown neither in predecidual cells nor in surface or glandular epithelia just prior to the menstruation. In addition, SOD activity was also shown in the decidual cells of 8 weeks gestation and in the reserve cells of the endocervix. Collectively, the present immunohistochemical recults suggest that SOD may play an important role not only in the protection of developing embryos from superoxide anion radicals but also in the local defense mechanism against tissue damages resulting from inflammation in the uterine cavity, and that the expression of SOD may be regulated by sex steroids, especially progestorone. Furthermore, SOD could be a useful indicator to clinically diagnose the degree of predecidualization and the luteal phase defect.The superoxide anion, a free radical generated during the monovalent metabolic reduction of oxygen, is toxic to the aerobic cell in which it is produced (13). The superoxide anion radical has been reported to damage cell membrane (22) and DNA (35), and to inactivate various enzymes (6). Also, it has been implicated in a variety of pathologic processes, including diabetes mellitus (11), lung damage (20), hepatitis (36), myocardial reperfusion injury following surgery (16), cataract (4), and so on. Therefore, effective detoxication of the superoxide anion radical appears to be a prerequisite for life in an oxygen-containing environment. Superoxide dismutase (SOD), known as superoxide oxidoreductase is an enzyme that catalyzes the dismutation (reduction/oxidation) of the superoxide anion radical in the following reaction: 2H+ +202 --k H202+02, and it is important as a biological defense mechanism against 487 488 Narimoto et al.cell injury mediated through superoxide anion radicals (12). In mammalians, three types of SOD have been identified which have different structures and metal contents: a cytoplasmic copper-zinc SOD (CuZn-SOD) (26), a mitochondrial manganese SOD (Mn-SOD) (3) and an extracellular SOD of high molecular weight (EC-SOD) (23).Mammalian preimplantation embryos grown in vitro are likely to exhibit sub-optimal or retarded development (45). In rodents, for example, the 2-cell block phenomenon, i.e., the proliferation arrest of f...

To prevent the extra-uterine discharge of transferred embryos, we directly inserted mouse embryos into the endometrial stroma (intra-endometrial embryo transfer). A 27G injection needle was inserted near the utero-tubal junction into the endometrial stroma. After removal of the needle, a glass micropipette was inserted and one embryo was transferred with a very small amount of culture medium. To determine the feasibility of this method, the uterine lumen was flushed with phosphate-buffered saline from the tubal ends immediately after transferring blastocysts into pseudopregnant mice on day 2 and day 4. The rates of recovery of embryos from the uterine lumen were 5.0% (1/20; day 4) and 15.0% (3/20; day 2). These results suggest that a high rate of intra-endometrial embryo transfer is possible. The embryonic viability rates (number of viable grown fetuses/number of blastocysts transferred) of this method were 50.0% (28/56; day 4) and 25.0% (5/20; day 2). Living offspring were delivered from both recipients which had received embryos on day 2 and day 4 of pseudopregnancy. In human in-vitro fertilization and embryo transfer, attempts have also been made to immobilize the embryos, and this method might be clinically applicable. Moreover, this method will be a good in-vivo model for studies on the mechanism of implantation.

Abstract.To elucidate whether or not the promoting effects on embryo development is derived from the characteristic factors which the oviduct possesses, we cultured mouse embryos in the oviduct, the ureter and the vein, all of which have "ductal structures", and we compared the culture efficacy among 3 organs. Furthermore, we measured oxygen tensions within the 3 organs and performed an ultrastructural analysis of the three ductal organs after the culture. Embryos cultured in the oviduct developed to blastocysts at a significantly higher rate (13.5%) than those in the ureter (1.7%) and the vein (0%). The oxygen tensions of the inner lumen of all the ductal organs were relatively low, 36-45 mmHg, and no remarkable difference was observed among the 3 organs. These results suggest that the oviduct may have embryo growth promoting effect besides low oxygen tension. Furthermore, the ultrastructural results suggest that not only the normality of structural components but the inherent character of the oviduct may play an important role in the promotion of embryo development.

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