An electron microscopic study of fetal capillary basal laminas of "normal" human term placentas.

Electron microscopic examination of terminal (free-floating) villi of definable normal human term placentas emphasizes the variable fine structural appearance of the fetal capillary basal lamina (FL). The FL assumes both a unilaminar and multilamellar configuration in each placenta examined; the multilamellar portions are usually composed of individual layers which tend to branch and anastomose. The constant indentification of collagen fibrillar profiles between these electron-dense layers argues against the notion that the multilamellar portions of the FL arise via a simple splitting or disaggregation of pre-existing unilaminar FL's.     

Lead and cadmium concentrations in maternal and umbilical cord blood, amniotic fluid, placenta, and amniotic membranes

The lead and cadmium concentrations in maternal and umbilical cord blood and amniotic fluid were determined in 19 parturient women at delivery. Six placental and amniotic membrane tissue specimens were also investigated. The mean lead concentrations (mean +/- SD) in maternal (40.4 +/- 18.2 ng/ml) and umbilical cord (37.1 +/- 13.5 ng/ml) blood were similar and correlated significantly with each other (r = 0.77, p less than 0.001). The lead concentration in amniotic fluid (59.6 +/- 8.3 ng/ml) was significantly higher than in maternal or umbilical cord blood. Cadmium concentrations in maternal blood (1.1 +/- 0.9 ng/ml) and amniotic fluid (1.0 +/- 0.2 ng/ml) were significantly higher (p less than 0.001) than in umbilical cord blood (0.4 +/- 0.2 ng/ml) and there was no significant correlation among these values. The highest concentrations of cadmium (35.1 +/- 24.2 ng/gm of wet weight) and lead (87.3 +/- 154.2 ng/gm of wet weight) were found in the amniotic membranes. Our results show that lead and cadmium accumulate in amniotic fluid and amniotic membranes and that the distribution of lead and cadmium is different in the human maternal-fetoplacental unit. The fetal exposure to lead is similar and that to cadmium, lower, compared with maternal exposure. The inability of the placenta to totally prevent the fetus from exposure to lead and cadmium suggests that pregnant women should avoid occupations where exposure to these toxic elements is possible.     

The human placenta in idiopathic intrauterine growth retardation: a light and electron microscopic study

Six placentae from small for gestational age infants were examined by both light and electron microscopy. These were from pregnancies in which all maternal or fetal factors known to be associated with intrauterine growth retardation, including maternal cigarette smoking, were excluded. At the light microscopic level the only significant finding was an excess of villous cytotrophoblastic cells whilst electron microscopy showed these placentae to be characterized by villous cytotrophoblastic hyperplasia, focal syncytial necrosis, microvillous abnormalities, reduced syncytial secretory activity, irregular thickening of the trophoblastic basement membrane and the presence of small fetal villous vessels with multilayered basement membranes. It is thought that most of the observed abnormalities are due to uteroplacental ischaemia and it is possible that the fetal vascular abnormalities are a reflection of the fetal growth retardation. There is little evidence that the functional efficiency of the placenta is impaired in these cases and it is suggested that the principal factor in the pathogenesis of fetal growth retardation is a restriction of nutrient supply to the fetus because of an inadequate degree of physiological change within the maternal spiral vessels.     

Ultrasound abnormalities of the amniotic fluid, membranes, umbilical cord, and placenta

Prenatal ultrasound has expanded the ability to assess the umbilical cord, fetal membranes, amniotic fluid volume, and placenta. Evaluation of these structures provides information regarding the intrauterine environment. Umbilical cord abnormalities may be associated with fetal aneuploidy, structural anomalies, and fetal compromise. Estimating the amniotic fluid volume has become an integral part of a sonogram and provides immense information regarding possible fetal anomalies and perinatal outcome. Likewise, placental location or abnormalities may significantly impact obstetric management and prognosis. Early detection of several of these conditions may lead to increased vigilance that may improve perinatal outcome.     

Concentration of annexin V in gestational tissues: placenta, fetal membranes, myometrium and amniotic fluid

THE BACKGROUND: It is believed that annexin V, an anticoagulant protein abundant in trophoblast, prevents circulating blood in the intervillous space from hypercoagulability and fibrin deposition. Distribution and the role of annexin V localized in other gestational tissues like myometrium and fetal membranes, as well as in amniotic fluid is unknown. The aim of this study was to determine the concentration of annexin V in the tissues under consideration. STUDY DESIGN: The study group consisted of 40 healthy women at the 1st stage of labour, 16 of whom delivered by cesarean section. The strips of myometrium, placenta and fetal membranes, as well as the samples of amniotic fluid and the venous blood, were collected during surgery. Homogenates were prepared from the tissues. Annexin V was measured by immunoenzymatic method (ELISA). RESULTS: Concentration of annexin V in the placenta was 122.65 +/- 33,14 ng/mg protein, in fetal membranes 136.31 +/- 49.30 ng/mg protein and in myometrium 65.40 +/- 30.72 ng/mg protein. There was a statistical difference between the concentrations in placenta and fetal membranes vs. myometrium (p<0.05). In amniotic fluid annexin V was found to be in low concentration (4.46 +/- 2.59 ng/ml, i.e., 1.60 +/- 1.21 ng/mg protein) while in blood plasma it was extremely low, over 6000 times lower than in placenta. CONCLUSION: Annexin V is present not only in placenta, but also in fetal membranes and myometrium. Its concentration in fetal membranes is similar to that in placenta, while in myometrium it is 50% lower. Annexin V found in newly discovered sites probably plays a similar role like placental annexin V.     

Light and electron microscopic investigations on the chorionic plate of the human placenta at term (author's transl)]

The chorionic plate of the human placenta at term consists of amniotic epithelium, amniotic connective tissue, intermediate layer, chorionic connective tissue, cytotrophoblast, and syncytiotrophoblast. - The connective tissue layers are divided into unorientated (situated just below the amniotic epithelium and in direct contact with the trophoblast) and orientated layers (between the two unorientated connective tissue layers). Besides an accelular border below the amniotic epithelium the connective tissue includes fibrocytes, fibroblasts, histiocytes, and old Hofbauer cells in the intermediate layer. - From the edge of the chorionic plate to its centre, the number of well preserved cytotrophoblasts decreases; instead of them especially intercellular substances (subchorial fibrinoid) but also degenerating cells predominate. In the trophoblast layer rests of chorionic villi are localized. Among the intact cytotrophoblasts 4 types can be distinguished (less differentiated, well differentiated, spongiotrophoblast-like, and glycogen-rich cytotrophoblastic cells). They are interpreted as different developmental stages of one and the same cell population. - The syncytiotrophoblast is inter rupted at many places; only fragments can be observed. Then cytotrophoblastic cells or intercellular substances may form the border to the intervillous space.     

Laminin distribution in human decidua and immature placenta. An immunoelectron microscopic study (avidin-biotin-peroxidase complex method)

An immunoelectron microscopic study was carried out on human placenta and decidua with the use of preembedding, the avidin-biotin-peroxidase complex technique, and rabbit anti-murine laminin antibody. Laminin was detected in the lamina lucida of basement membrane of placental villi, amniotic membranes, umbilical cord, endometrial glands, and blood vessels. No positive laminin immunostaining was observed in intracytoplasmic organelles. However, positive immunostaining surrounded decidual cells as a more or less continuous linear membrane. It is suggested that laminin, as a component of this basement membrane-like material that has already been reported in decidual cells, may be related to the hormonal stimulation occurring during pregnancy and trophoblastic attachment.     

Localization of glycogen in the placenta of diabetic rats: a light and electron microscopic study

The ultrastructure of the placentae on day 20 of gestation was studied in rats made diabetic by streptozotocin injection on day 13 of gestation. In the placentae of control rats most of the glycogen was found in the glycogen cells, while some of it was localized to the labyrinth trophoblastic layers. In the diabetic rats a marked increase in glycogen content, together with higher numbers of glycogen cells in the junctional zone, was seen. Glycogen was also stored in other cell types of this zone, as well as in all cell types of the placental labyrinth of the diabetic animals.     

Human term placenta releases placental protein 10 (PP10) in tissue culture

Placenta, decidua, chorion and amnion were studied to determine the tissue concentration of placental protein 10 (PP10). As measured by radio-immunoassay, all tissues studied were found to contain approximately the same concentration of PP10, in both early and late pregnancy. The release of PP10 was studied in tissue culture, first by using explants of placenta, decidua, amnion and chorion in four preliminary studies. Only the placenta released significant amounts of PP10 into the culture medium and, therefore, further studies were carried out with placental explants. In gel filtration, the bulk of PP10 in the culture medium eluted in the same position as purified PP10, and the dose-response curves of the two materials were parallel. The total secretion of PP10 into the culture medium was studied throughout 96 hours of incubation. Cycloheximide, a protein synthesis inhibitor, reduced the release of PP10 into medium by 31.3 +/- 12.5%. In cycloheximide-treated tissue cultures, the secretion of PP10 recovered when cycloheximide was replaced by original culture medium without cycloheximide. There results show that placenta is a major source of PP10.     

Decidualisation of the endometrial stromal cell. An electron microscopic study (author's transl)

The fine structural changes of the endometrial stromal cell from late secretory phase up to full developed decidua cell have been investigated by means of electron microscope. During decidual transformation the cell volume, the assortment of cytoplasmic organelles and the mode of intercellular attachments undergo characteristic alterations. These alterations reflect an adaptation on new cellular functions. In contrast to the structural organization, which is transformed continuosly, the encymatic cell pattern exerts a step wise gradual transformation, since new encymatic capacities can only arise after their funtional structures have been established. To the most important functions of decidua cells and their prestages belong secretory and endocrine activities. Precollagen fibrills represent a specific secretory product of the stroma reticulum cells. The active involvement of the full differentiated decidua cells in steroid metabolism is indicated by characteristic transformation of the cytoplasmic organization concomittantly to the appearance of intracellular steroid dehydrogenase activities. So-called karyosoma could be demonstrated within the nuclei of postovulatory stromal reticulum cells as in decidua cells. Similar nuclear differentiations have been observed in various target cells of steroid hormones. They possibly are structural manifestations of the hormonal interaction with the nuclear DNA.     

High-affinity, calcium-stimulated ATPase in brush border membranes of the human term placenta

ATPase activity which is stimulated by submicromolar concentrations of calcium (Ca2+) was identified in human placental microvillous brush border membranes. The high-affinity enzyme has an apparent K0.5 for free Ca2+ of 18.3 +/- 3.7 nM and a Vmax of 233.0 +/- 30.0 nmol/min/mg protein. Studies using trans-1,2-diaminocyclohexane-N,N,N1,N1-tetraacetic acid (CDTA) show that this enzyme requires submicromolar concentrations of Mg2+ for maximal activity, but that it appears to have a low basal activity in the absence of this cation. The high-affinity Ca2+-ATPase was unaffected by up to 100 microM concentrations of vanadate, but was sensitive to trifluoperazine inhibition (I50 less than 50 microM). It was not found to be stimulated by the addition of up to 10 micrograms calmodulin, but this lack of effect may be related to the endogenous calmodulin content of the membrane preparation. A low-affinity, non-specific divalent cation ATPase was also identified in this membrane preparation. In contrast to the high-affinity enzyme, it has an apparent K0.5 for calcium of 99.7 +/- 22.1 microM, and a Vmax of 1.54 +/- 0.17 mumol/min/mg protein. The characteristics of the high-affinity Ca2-ATPase are similar to those of other Ca2+- ATPases known to transport and regulate intracellular calcium concentrations in other tissues. By analogy, we suggest that the high-affinity Ca2+-ATPase described here could play an important role in cellular calcium homeostasis in the human placenta.     

Ovarian fibroma with Leydig cell hyperplasia of the adjacent stroma: a light and electron microscopic study

A virilizing left ovarian tumor removed from a 58-year-old woman was studied by light and electron microscopy. Histologically, the tumor was an ovarian fibroma around which Leydig cells, but no Sertoli cells, proliferated at a distance from the hilus. Although the fibroma itself did not contain Leydig cells, several Leydig cells were observed intermingled with ovarian stromal cells in the cortical tissue compressed by the fibroma. Ultrastructurally, in addition to mature Leydig cells with typical steroid-producing--cell features, immature cells with less-developed smooth endoplasmic reticulum and elementary tubular inclusions were identified. These light and electron microscopic findings suggest that the Leydig cells may have differentiated from ovarian stromal cells surrounding the fibroma. If so, this case should be distinguished from neoplastic disorders such as hilar cell tumors or stromal-Leydig cell tumors and be classified in the category of ovarian tumors with functioning stroma containing Leydig cells.     

Papillary serous tumors of the ovary: An electron microscopic study

Fifteen papillary cystic tumors of the ovary were studied by electron microscopy. These consisted of eight serous cystadenocarcinomas, one recurrent cystadenocarcinoma, one borderline tumor, and five benign cystadenomata. Multiple samples were studied both by light and electron microscopy. Electron microscopic criteria previously described as useful in distinguishing between benign and malignant lesions were not found to be sufficiently consistent to be useful.