[Clinical aspects of premature detachment of the placenta, placenta accreta and placenta increta (author's transl)].
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Abruptio Placentae↗
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[The importance of regressive changes in the placenta during the so-called migration of the placenta (author's transl)].
Starting from the tenth to the sixteenth week of pregnancy ultrasonic placental localizations were performed in 22 pregnant women at four week intervals. In all cases the placenta was located in the anterior wall of the uterus and bordered or covered the internal os of the cervix. In 17 cases a cephalad migration of the placental localization was registered. In 5 cases the low implantation of the placenta did not change until delivery. In 14 of 19 cases marginal atrophic changes of the placenta were found. No morphologic abnormality was detected in five placentas from patients who showed migration of the placental localization. Since the placenta is tightly implanted in the endometrium a true migration of the placenta is unlikely. Our investigations show that areas of low implantation of the placenta are stretched with increasing growth of the uterus and then undergo regressive and pressure atrophy changes. It is likely that the cervical margin of the placenta cannot be detected by ultrasound in a large number of cases.
Atrophy↗
[Quantitative investigations of the human placenta under normal conditions and in case of preeclampsia correlated to the human placenta-lactogen blood-level in the last third of pregnancy (author's transl)].
Thirty-two human placentas from normal and from pregnancies complicated by preeclampsia in last third of gestation were morphologically and morphometrically examined and correlated with human placenta-lactogen blood-level. HPL was determined by the radio-immunoassay (Carbon-Dextran-method). HPL-values, placenta villous surface, the weight of the newborn and placenta showed significant correlation. The placentas were classified according to the morphologic degree of severity (placenta-morphological-index) and compared to preeclamptic index (Goecke) and HPL-values. The results showed correlation between the studied datas according to the severity of preeclampsia. The significance of these results is discussed.
Birth Weight↗
Monoamine oxidase in rat placenta, human placenta, and cultured choriocarcinoma.
The activity of monoamine oxidase (MAO), an enzyme which metabolized catecholamines and indoleamines, was determined in rat placenta at various stages of gestation, in human term placenta, and in choriocarcinoma grown in culture. From Day 15 to Day 20 of gestation the specific activity (units/mg protein) of MAO in rat placenta increased at least 3-fold; from Day 20 to the time of parturition, it decreased about 50%. The specific activity of MAO in human placenta at term was about 50%. The specific activity of MAO in human placenta at term was about 8 times higher than that of rat placenta at term. No MAO activity was found in choriocarcinoma grown in culture.
Animals↗
Relationship of the sex of the foetus to the amount of human chorionic gonadotrophin in placentae; single and dizygotic twin placentae compared.
Human chorionic gonadotrophin (HCG) was assayed by biological and radioimmunological methods in placentae from 16 women with a normal twin pregnancy. When the concentration and total amount of HCG in placentae was related to the sex of the twin foetus, no significant difference between 'male' and 'female' placentae was found. This is contrary to findings that there is a significant (P less than 0-005) difference in the concentration of HCG per g and per placenta of singletons at term. A comparison between the grouped geometric mean data from bioassays shows that the amount of HCG per g and per placenta falls between the geometric mean values for 'male' and 'female' singleton placentae.
Adult↗
Development of trophoblast and placenta of the mouse. A reinvestigation with regard to the in vitro culture of mouse trophoblast and placenta.
At 5 days post conceptionem (p.c.) shortly after implantation, giant cell transformation starts at the abembryonic pole of the blastocyst, spreading over the mural trophoblast; 1 day later, the first ectoplacental giant cells appear at the base of the fast growing ectoplacental cone (derived from the polar trophoblast). Giant cell transformation expands over it periphery. Thus, by the 8th day p.c., the conceptus is separated from the maternal tissue by a continuous layer of giant cells, variable in thickness. Giant cells reach their greatest size by 10 days p.c. in the mural tophoblast and by 12 days p.c. in the chorioallantoic placenta. They are probably no longer formed after that stage. Around the 8th day p.c., the allantois reaches contact with the ectoplacental cone, which develops into the chorioallantoic (definitive) placenta. At 9 days p.c., its four zones can already be discriminated: chorionic plate, labyrinth, junctional zone (trophospongium), and zone of giant cells, respectively. Within the next day, the chorioallantoic placental circulation is established. The yolk sac placental circulation is established by the 9th day p.c. The villi of the proximal layer of the yolk sac increase in size and number, and their capillary network becomes more dense until the 12th to 14th day p.c. This provides evidence that the yolk sac placenta exerts its function--to a certain extent--beyond the establishment of the definitive placenta. Around the 14th day p.c., the placental labyrinth reaches its definitive features. Fetal capillaries in the labyrinth, branching from unbilical blood vessels within the septa of connective tissue are surrounded by trophoblast cells. They form a dense vascular network bathing in maternal blood. The structures of the placental zones remain almost the same during further development, the borders becoming sometimes little blurred. Adjacent to the chorionic plate, subchorionic clefts appear at the 14th day p.c. These clefts become confluent to form the intraplacental space, regularly communicating with the yolk sac cavity. At the end of gestation (19th day p.c.) there is a considerable amount of eosinophilic material ('fibrinoid') between the zone of giant cells and the decidua, probably produced by the giant cells.
Animals↗
Studies of beta-glucuronidase in first-trimester placenta, term placenta and hydatidiform mole.
The specific activity and isoenzyme pattern of beta-glucuronidase (beta-D-glucuronide glucurononosohydrolase, EC 3.2.1.31) from first-trimester placenta, term placenta and hydatidiform mole were compared. Enzyme activity is highest in term placenta and lowest in hydatidiform mole, reflecting the steroid conjugation requirements of the tissues. The difference in enzyme activity is due to variation in the level of one isoenzyme form (isoenzyme B) of beta-glucuronidase, which is absent in molar tissue. The possible cause for the changing isoenzyme pattern is discussed.
Female↗
Mechanism of action of Zn2+ and Mg2+ on rat placenta alkaline phosphatase. II. Studies on membrane-bound phosphatase in tissue sections and in whole placenta.
Alkaline phosphatase (EC 3.1.3.1) bound to trophoblastic cells in rat placenta is activated by Mg2+ and inhibited by Zn2+ in the same way as is found with partially purified soluble alkaline phosphatase in the same tissue (PetitClerc, C., Delisle, M., Martel, M., Fecteau, C. & Brière, N. (1975) Can. J. Biochem. 53, 1089-1100). In studies done with tissue sections (6-10 micron), it is shown that alkaline phosphatase activity and labelling of active sites by orthophosphate are lost during incubation with ethanolamine at pH 9.0. Addition of Mg2+ causes total recovery of catalytic activity and active sites labelling. Zn2+ displaces and replaces at the Mg2+ binding sites. The affinity for both ions is similar, and dissociation of Zn2+ from the enzyme is a very slow process, even in the presence of Mg2+. The Zn2+-alkaline phosphatase and Mg2+-alkaline phosphatase, which only differ by the ion bound to an apparent modulator site, have the same catalytic activity at pH less than 7.0, but the Zn2+ species has little activity at alkaline pH. Phosphorylation of the enzyme by orthophosphate indicates that with both enzyme species phosphoryl intermediate does not accumulate at alkaline pH. These results suggest that with orthophosphate, the phosphorylation step is rate determining for both enzymes, and that Zn2+ affects this step to a much greater extent. It is proposed that Zn2+ and Mg2+ regulate alkaline phosphatase in rat placenta. The concentration of both ions in maternal serum and placenta suggest that such a mechanism could exist in vivo.
Alkaline Phosphatase↗
The passage of thiamine across the rat placenta and its uptake by the fetal organs. I. The transport of thiamine across the placenta.
It is well known that thiamine is highly soluble in water. However, if chloroplatinic acid (H2PtCl6) is used during fixation, an insoluble, electron-dense thiamine-PtCl6 precipitate is formed. Using this method we performed electron microscope autoradiography of the placental labyrinth of rats in their 15th day of pregnancy after injection into the maternal bloodstream of 3H-thiamine, and we also measured the radioactivity of the tissues, in order to study the transport of the thiamine across the placenta. Both developed silver grains and radioactivity were found in the largest amounts 30 min after injection; the amounts of both declined after 2 hrs and declined further after 5 hrs. The majority of the developed silver grains were localized in the smooth-surfaced endoplasmic reticulum, which is generally thought to be the vehicle for the transport of materials in the cell, while in the mitochondria, Golgi apparatus, etc. the grains were few. Considering the substantial depletion of the amounts of both sivler grains and radioactivity after the relatively short time of 5 hrs, we conclude that the greater portion of the thiamine passes quickly across the placenta to the fetus, where it is used in the metabolism of the fetal organs, and that only a small part of the thiamine is retained in the placenta for its own metabolism.
Animals↗
Water and ion metabolism in placenta. II. Water compartments and electrolytes in slices of rabbit placenta, at different periods of gestation, incubated at 0-1 degree C.
The movement and the distribution of water, sodium, potassium, chloride, magnesium and calcium have been studied in slices prepared from rabbit placentae at different periods of gestation, incubated in condition of depressed metabolism (0-1 degree C). In these conditions the tissue takes up water from the external medium up to a maximum of about 2.0 kg/kg d. wt., which represents 30 per cent of the initial H2O content of the fresh tissue. The extracellular compartment swells progressively and proportionally to the age of the placenta. The sodium and chloride content of the tissue increases while that of potassium decreases and their intracellular concentration reaches, after 120 min, that of the external medium. Magnesium does not show appreciable changes and calcium, too, despite its extreme variability, does not seem to undergo significant variations during the cold incubation. The results obtained show that placenta, like most of other mammalian cell systems, possesses specific metabolism-dependent mechanisms responsible for the maintenance of water distribution and ion gradients among the different tissue compartments. The characteristics and the regulation of these mechanisms are discussed in detail.
Animals↗
Bovine retained placenta: effects of collagenase and hyaluronidase on detachment of placenta.
A significant percentage of cows (11%) fail to release the placenta within 12 h postpartum. Failure of collagen breakdown seems to be related to the retention of placentas. Sections of placentomes incubated with bacterial collagenase caused an increase in placentome proteolysis (6.6-fold) and placentome collagenolysis (94-fold) within 4 h in a dose-related fashion (r = 0.94). Injections of collagenase (825 U/cc) into the placentomes, via umbilical vessels, decreased the cotyledon-caruncle binding force (determined by manometry) to 30 +/- 5 mm Hg from 97 +/- 2 mm Hg, and increased proteolysis by 42% within 8 h (r = -0.95). Hyaluronidase at various concentrations (400-8 250 U/cc) and at various incubation times (up to 8 h) was not effective. Hyaluronidase (825 U/cc) and collagenase (825 U/cc) were not synergistic in loosening cotyledon-caruncle attachment. A single 15-min collagenase pulse, given prior to perfusion with collagenase-free blood, was as effective in loosening cotyledon attachment as was a sustained 2-h perfusion of blood with collagenase added. It was concluded that collagenase caused collagenolysis and loosening of cotyledon from caruncle, but collagenolysis and cotyledon-caruncle separation were not facilitated by the presence of hyaluronidase.
Animals↗
Glycosphingolipid expression in spontaneously aborted fetuses and placenta from blood group p women. Evidence for placenta being the primary target for anti-Tja-antibodies.
A 12-week-old fetus and one 17-week-old fetus + placenta were obtained after spontaneous abortions from two women of blood group p. The 17-week-old fetus was dissected into intestine, liver, brain and residual tissue. Nonacid glycosphingolipid fractions were prepared from the tissues. Glycolipid characterization was carried out using thin layer chromatography immunostained with monoclonal antibodies and bacteria and by 1H NMR spectroscopy and mass spectrometry. In the placental fraction substantial amounts of globotetraosylceramide (P-antigen) and globotriaosylceramide (Pk-antigen) were identified. In contrast, the fetuses contained only trace amounts of these structures, as revealed by immunostaining. These results indicate that the primary target for the antibodies of the anti-Tja serum is the placenta tissue, resulting in termination of the pregnancy.
Abortion, Spontaneous↗
Quantitative morphology of the placenta. II. The growth of the placenta and the problem of postmaturity.
The morphological changes in the placenta concomitant with the transition from maturity to postmaturity were investigated by stereology under early clamping of the umbilical cord. 37 placentas from nonpathological pregnancies delivered after a period of 224-303 days of amenorrhea were examined. It appeared that after 267-288 days of amenorrhea, 8 out of 9 placental components showed no further growth and even showed regression. Only the volume of the trophoblast continued to grow in postmaturity. It is suggested that during postmaturity the villous capacity to produce steroids is continuing at a normal rate (as judged by the increase of the volume of the trophoblast), whereas the capability to transfer is deteriorating (as testified by the decreasing surface of the trophoblast).
Chorionic Villi↗
Quantitative morphology of the placenta. III. The growth of the placenta and its relationship to birth weight.
The relationship of placental components to birth weight was investigated by stereology. 37 placentas from nonpathological pregnancies delivered after a period of 224-303 days of amenorrhea were examined. The umbilical cord was clamped immediately after birth. The ratios of the volume, the surface, the length of the villous vessels and the surface of the villi with birth weight showed a decrease after 277 days of amenorrhea. In contrast to this decrease, the ratio of the volume of the trophoblast with birth weight seems to increase. No difference could be found for the ratios of the placental volume (placental index), the volume of the villous tissue, the volume of the intervillous space and the volume of the nonfunctional tissue with birth weight. These ratios reveal a quantitative morphological base for the clinical experience that postmature fetuses are at a higher risk through deterioration of the placenta.
Birth Weight↗
Oncornavirus-like particles in squirrel monkey (Saimiri sciureus) placenta and placenta culture.
Oncornavirus-like particles similar in morphology to type D particles were observed in 1 of 2 squirrel monkey (Saimiri sciureus) placentas. Intracytoplasmic type A particles, immature virus particles, and mature viruses with eccentric or occasionally centric nucleoids were associated with placental syncytiotrophoblasts. A spike layer typical of type B viruses was not detected in viral envelopes. Onvornaviruses, identical to those previously isolated from squirrel monkey tissues and similar to Mason-Pfizer monkey virus, were seen in cultures derived from the virus-positive squirrel monkey placenta cocultivated with a mink lung culture. The major morphologic difference between the in vivo and the in vitro squirrel monkey virus was in the nucleoid position of mature virus particles.
Animals↗
Ultrastructure of the human placenta at term. Observations on placentas from newborn children of smoking and non-smoking mothers.
The placenta was chosen as a possible model for evaluating the vascular injury and tissue injury provoked by tobacco smoking in the human body. Full term placentas from 4 smokers and 3 non-smokers were studied in the transmission electron microscope. Pronounced changes were found in the group of smokers. The characteristic findings were broadening of the basement membrane of the placental villus, increase in collagen content of the villus, decrease in vascularisation and intimal changes in the villous capillaries and arterioles, with pronounced intimal oedema. Since similar changes have been reported previously from human umbilical arteries, and since these changes also can be induced in animal arteries by exposure to carbon monoxide or perfusion with nicotine, this study supports the concept that tobacco smoking is harmful to the human vascular system and tissues.
Adolescent↗
[Clinical aspects and morphology of placenta increta and placenta percreta (two case examples) (author's transl)].
The cases of a female patient with placenta increta and of another patient with placenta percreta and rupture of the uterus are presented. Both women were 41 years old, multiparae and had a history of multiple abortions as well as a Caesarean section. In both cases a Caesarean section, followed by a hysterectomy and supracervical amputation of the uterus respectively was done. Frequency, clinical aspects, histology and aetiology of the above described disorders of placentation are discussed.
Adult↗
In vitro perfusion studies of the human placenta. IV. Some characteristics of the glucose transport system in the human placenta.
In vitro perfusion studies of glucose transport in the human placenta show saturation kinetics at high glucose concentrations and competitive inhibition of glucose transfer by the nonmetablizable glucose analog 3-O-methyl-alpha-D glucopyranoside. These characteristics provide further evidence that glucose is transported by a facilitated diffusion process in the human placenta.
Biological Transport↗