Toshiro Tominaga

Accommodation of the human placenta to hypoxia

Abstract In the perfused, term human placenta, the fetal circulation responds to hypoxia by a marked vasodilatation and to a high oxygen concentration by vasoconstriction. This is interpreted as a rapid accommodation resulting in alterations of the effective area for oxygen exchange. When terminal villi are explanted for organ culture, and the concentration of oxygen in the chamber is reduced from 26 to 6 per cent, morphologic changes occur in the syncytiotrophoblast. The nuclei, together with some cytoplasm, cluster at one pole of the villus, leaving only a thin layer of cytoplasm over the basement membrane. The distance from the intervillous space to the nearest fetal capillary is reduced by 25 per cent. In accordance with the law governing diffusion, such a change should permit a comparable increase in the quantity of oxygen transferred per unit of time. The clustering of nuclei and thinning of the syncytial covering is quite marked by 6 hours. If normal oxygen concentration is now restored, the morphologic changes are largely reversible. The changes are interpreted as a slow accommodation of the placenta to chronic hypoxia. The nuclear clustering and “naked” villi are quite identical to those observed in the majority of villi of placentas from women with pre-eclampsia or eclampsia.

Sex chromatin of trophoblastic tumors.

Abstract The incidence of sex chromatin was determined in 48 trophoblastic tumors. Of 30 cases of hydatidiform mole and chorioadenoma destruens, 29 (97 per cent) were sex chromatin positive or female. Fourteen (78 per cent) of 18 choriocarcinomas were also sex chromatin positive. It is concluded that most benign trophoblastic tumors have an XX constitution, whereas true choriocarcinoma arises by chance. The literature is reviewed, and various immunologic and genetic theories which bear upon these findings are discussed.

Left renal pelvis of male neonates is predisposed to dilatation

Dilatation of the renal pelvis has been observed as an ultrasonographic finding of ureteral reflux as well as hydronephrosis. However, little information is available on the prevalence of renal pelvis dilatation in neonates. We measured the inner pelvis dimension of the kidneys in 511 apparently healthy neonates (279 boys and 232 girls) using an ultrasound scanner to determine the prevalence of renal pelvis dilatation. Ninety per cent of the neonates had an inner dimension of both renal pelvises below 5 mm. The prevalence of left renal pelvis dilatation of 5 mm or more was significantly higher in the boys than in the girls, 25 (9%) compared to 5 (2%). In contrast, no significant difference was found in the prevalence of right renal pelvis dilatation between the sexes. In the boys, the prevalence of renal pelvis dilatation of 6 mm or more was significantly higher on the left side than on the right. Moreover, the left renal pelvis dilatation of the male neonates had a tendency to persist at 1 month of age. These findings suggest that the left renal pelvis of the baby boy may be predisposed to dilatation.

Therapeutic effects of danazol on endometrial cells may be activated by the presence of extracellular matrix

OBJECTIVE To demonstrate the direct effect of danazol on the endometrium in the presence of various types of extracellular matrix. STUDY DESIGN Human endometrial cells (epithelial and stromal cells) were cultured over various extracellular matrix in the absence or presence of danazol. The effects of danazol on the growth of endometrial cells and the specific glandular structure were studied. RESULTS Danazol (10(-7) mol/L) inhibited endometrial cell growth, and in the presence of Matrigel, the same danazol concentration demonstrated a stronger inhibitory effect on epithelial cell growth. Danazol inhibited the formation of the specific glandular structure. Its effect depended on the culture substrates used and was reversible. Danazol did not inhibit growth of cells cultured over type V collagen substrate, whereas growth of those grown over type IV collagen was greatly inhibited. CONCLUSION The results indicate that a distinctive extracellular matrix around ectopic endometriotic tissue modulates cell growth and differentiation. Endometrium associated with a normal extracellular matrix is apparently protected from therapeutic drugs, whereas endometriotic tissue growing over a deranged extracellular matrix would be sensitive to therapeutic drugs, such as danazol.

At what stage does the embryo begin to grow larger in frozen-thawed embryo transfers?: fetal development from the standpoint of gestational sac diameter and birth weight

Abstract: Frozen-thawed embryo transfers, whose number has risen considerably in recent years, reportedly result in heavier birth weights than fresh embryo transfers. To find out what this difference means and the stage at which it becomes manifest during fetal development, we studied birth weight and gestational sac size, which reflects development immediately following implantation, in 365 single pregnancies employing fresh embryo transfer and 227 employing frozen-thawed embryo transfer. Comparison of fresh embryo transfers and frozen-thawed embryo transfers revealed that average birth weights were significantly higher in the latter, with average values ± SD of 2896.0 ± 515.7 g and 3060.0 ± 529.2 g, respectively. Transvaginal ultrasound showed significantly larger average gestational sac diameters at 21, 22, 23, 28, 29 and 30 days after fertilization in frozen-thawed embryo transfers. We speculate these results are explained mainly by hormone replacement therapy in frozen-thawed embryo transfer cycles exerting a more positive influence on the endometrium, promoting smoother implantation, greater development during early pregnancy, and significant increases in birth weight. Amidst concerns regarding the impact exerted on fetuses by the artificial operations entailed by in vitro fertilization and embryo transfers, these findings may serve as evidence of the safety of frozen-thawed embryo transfers.