Blood flow in the umbilical artery in physiological pregnancy

Fetal umbilical artery flow was measured with Doppler ultrasound technique in 206 cases of the uncomplicated pregnancy. Indices A/B and R.I. were calculated. It was shown that vascular resistance in the umbilical artery is decreasing in the normal pregnancy parallel to its development and is manifested by the changes in A/B and R.I. values.     

Electron-microscopic and immunocytochemical analyses of Weibel-Palade bodies in the human umbilical vein during pregnancy

Summary The present study was done to elucidate the biological significance of the Weibel-Palade body of human umbilical vein endothelial cells. Quantitative determinations of these endothelial-specific granules throughout pregnancy revealed that their numbers and size per cell profile were maintained at low levels from 12 to 19 weeks of gestation; then both rapidly increased from 33 weeks to full term. This increase coincided with the development of the rough endoplasmic reticulum and an increase in the number of endothelial cell pinocytotic vesicles. Light-microscopic peroxidase anti-peroxidase and electron-microscopic protein A-gold techniques provided evidence that factor VIII-related antigen was localized in the Weibel-Palade bodies. Furthermore, in vitro treatment of incubated umbilical vein tissue with compound 48/80, a histamine releaser, induced degranulation of Weibel-Palade bodies from the endothelium. The present study indicates that Weibel-Palade bodies are storage sites of both histamine and factor VIII-related antigen and have an important role in the obliteration of this vessel.     

Blood flow in ductus venosus in early uncomplicated pregnancy

The ductus venosus is the very important part of fetal venous circulation. It plays a central role in return of venous blood from the placenta. This unique shunt carries well-oxygenated blood from the umbilical vein through the inferior atrial inlet on its way across the foramen ovale. Using Doppler ultrasound, it is possible to assess the blood flow in fetal vessels including ductus venosus. It is observed, in animal and human studies, that the typical waveform for blood flow in ductus venosus in early pregnancy can be different depending on numerous conditions e.g. fetal karyotype. This study is performed to assess the physiologic parameters of blood flow in ductus venosus in uncomplicated early pregnancy. Material and Methods: 404 women were examined between 11+0 and 13+6 weeks (+ days) of gestation by ultrasound. Fetal crown-rump length (CRL) was measured to assess the gestational age. The assessment of risk of fetal abnormalities was based on nuchal translucency (NT) measurement. The ductus venosus blood flow with color and spectral Doppler was obtained in all patients. The following features were assessed: pulsatility index (PI), and direction of flow (positive/negative) during atrial contraction (wave A). All cases were followed up to 22 weeks of gestation when the control scan was performed. Results and conclusions: 30 cases were excluded from the uncomplicated group due to: high risk of fetal abnormalities, fetal loss, confirmed fetal abnormalities and utero-placental pathology. 374 women were considered as uncomplicated pregnancy. In both uncomplicated and complicated groups the mean values for pulsatility index (PI) were established. The mean PI value in uncomplicated pregnancies was: 0.91 (SD +/- 0.32). No significant differences between groups were noticed. In 370 cases of uncomplicated pregnancy the A wave direction was positive but in 1.1% of cases the reverse flow in atrial contraction was observed.     

Transrectal Doppler sonography of uterine and umbilical blood flow during pregnancy in mares

Transrectal color Doppler sonography was used to investigate uterine and umbilical blood flow during pregnancy (duration, 46-48 weeks) in four mares. The resistance index (RI) and blood flow volume (VOL) of the uterine arteries ipsilateral and contralateral to the conceptus, and the presence of an early diastolic notch in the Doppler wave, were evaluated every 4 week throughout pregnancy. Fetal blood flow was calculated semiquantitatively every 2 week (from 20 to 40 weeks), using the RI of the umbilical arteries. During the entire period of investigation, there were no significant individual variations in uterine RI and VOL nor differences between the two uterine arteries. Mean RI decreased by more than half during pregnancy from 0.89 +/- 0.01 to 0.39 +/- 0.03, and mean VOL increased almost 400-fold from 69 +/- 37 to 27,467 +/- 8851 ml/min. There were relationships (P<0.0001) between week of pregnancy (x) and RI as well as VOL. These were described by the equations RI=0.938-0.150 ln(x) and VOL (ml/min)=7.621x(2.157). Log transformed total estrogen (TE) were related to RI (r=-0.879; P<0.05) as well as to VOL (r=0.888; P<0.05). The notch in the Doppler wave of the uterine artery disappeared between 18 and 26 weeks. There was a correlation (P<0.0001) between week of gestation (x) and RI values of the umbilical arteries; this was described by the equation RI=1.763-0.071x+0.001x2. Further studies are needed to determine whether transrectal color Doppler sonography could be used to identify mares at risk of abortion.     

Element content of human umbilical artery and vein in umbilical cord

To elucidate the element content of newborn blood vessels, umbilical arteries and veins in human umbilical cords, which had the advantage of easy sampling, were examined by ICP-AES. Umbilical cords were removed after birth. Mothers’ ages ranged from 26 to 35 yr. It was found that the content of sulfur was the highest in both umbilical arteries and veins, being higher than the content of calcium and phosphorus. With respect of the content of sulfur, calcium, and magnesium, there were significant differences between the arteries and veins.     

Blood flow distribution in the branches of frog mesentery arterial microvessels]

The blood flow distribution in 49 arterial branchings of the mesentery (R. temporaria) was investigated (D of the trunk = 25.7 + 0.0 mum). Linear rate was measured by the impulse digital chronometry of the intervals of the erythrocyte transit time. The geometric characteristics of the branching was determined in vivo, on photographs. An asymmetric structure of the investigated branching was shown; branch 1 had the inner initial cross-section which was 2.2 times greater than that of branch 2 and lesser turning angles (29 and 59 degrees). The blood flow in branch 1 was three times greater than the blood flow in branch 2; this was due to its greater inner initial cross-section and a higher linear rate. According to calculations, the blood flow resistance of the branch-turn was insignificant in the general blood flow resistance of branches; therefore the turning angle of the branches could not serve as an important regulator of the volume of the blood flowing in them. An experimentally revealed association between the blood flow in the branches, their radius and their turning angles is well described by equations of the "optimal" model of the vessel branching.     

Pressure and flow in the umbilical cord

A fluid dynamic study of blood flow within the umbilical vessels of the human maternal-fetal circulatory system is considered. It is found that the umbilical coiling index (UCI) is unable to distinguish between cords of significantly varying pressure and flow characteristics, which are typically determined by the vessel curvature, torsion and length. Larger scale geometric non-uniformities superposed over the inherent coiling, including cords exhibiting width and/or local UCI variations as well as loose true knots, typically produce a small effect on the total pressure drop. Crucially, this implies that a helical geometry of mean coiling may be used to determine the steady vessel pressure drop through a more complex cord. The presence of vessel constriction, however, drastically increases the steady pressure drop and alters the flow profile. For pulsatile-flow within the arteries, the steady pressure approximates the time-averaged value with high accuracy over a wide range of cords. Furthermore, the relative peak systolic pressure measured over the period is virtually constant and approximately 25% below the equivalent straight-pipe value for a large range of non-straight vessels. Interestingly, this suggests that the presence of vessel helicity dampens extreme pressures within the arterial cycle and may provide another possible evolutionary benefit to the coiled structure of the cord.     

Contact microscopic and histochemical studies of the placenta in normal and pathological pregnancy]

The placenta was studied in 70 women: 19 of them had physiological pregnancy and 51 had pregnancy complicated with late toxicosis. Lesions in the placenta have been shown to increase with the growing severity of toxicosis, and compensatory potencies--to decrease. In late toxicosis the expansion of desorganization and reparation in the placenta occurs from the center towards periphery, the peripheral parts playing the role of reserved zones of the placenta, keeping high functional activity.