A microphysiological model of the human placental barrier

During human pregnancy, the fetal circulation is separated from maternal blood in the placenta by two cell layers - the fetal capillary endothelium and placental trophoblast. This placental barrier plays an essential role in fetal development and health by tightly regulating the exchange of endogenous and exogenous materials between the mother and the fetus. Here we present a microengineered device that provides a novel platform to mimic the structural and functional complexity of this specialized tissue in vitro. Our model is created in a multilayered microfluidic system that enables co-culture of human trophoblast cells and human fetal endothelial cells in a physiologically relevant spatial arrangement to replicate the characteristic architecture of the human placental barrier. We have engineered this co-culture model to induce progressive fusion of trophoblast cells and to form a syncytialized epithelium that resembles the syncytiotrophoblast in vivo. Our system also allows the cultured trophoblasts to form dense microvilli under dynamic flow conditions and to reconstitute expression and physiological localization of membrane transport proteins, such as glucose transporters (GLUTs), critical to the barrier function of the placenta. To provide a proof-of-principle for using this microdevice to recapitulate native function of the placental barrier, we demonstrated physiological transport of glucose across the microengineered maternal-fetal interface. Importantly, the rate of maternal-to-fetal glucose transfer in this system closely approximated that measured in ex vivo perfused human placentas. Our "placenta-on-a-chip" platform represents an important advance in the development of new technologies to model and study the physiological complexity of the human placenta for a wide variety of applications.

Modelling nutrient transfer based on 3D imaging of the human placental microstructure

Impaired transfer of nutrients from mother to fetus can affect pregnancy outcomes. The placenta has a complex microstructure, including the maternal intervillous space and fetal capillaries. Previous computational models of placental transfer either assumed a simplified idealized local geometry or were based on 2D imaging. In this study, we present a novel 3D computational model to assess the placental transfer of nutrients at the microscale in interaction with the maternal flow environment. A stack of confocal microscopy images of the placental terminal villi was collected and reconstructed. The 3D simulation framework was tested for the transport of oxygen. Preliminary results identified local stagnant zones, as well as areas of high nutrient transfer into the fetal capillaries in the most exposed branches of the villi as a result of better perfusion, combined with a smaller thickness of the tissue barrier. Overall, the current model may serve as a tool for assessing pregnancy conditions affected by inefficient nutrient transfer due to altered microscale placental morphology.

[HISTOLOGYCAL AND HISTOCHEMICAL CHARACTERISTICS OF AREOLAE IN THE PIG PLACENTA]

Rounded white lustreless dome-shaped wheels are detected by visually from allantochorion side in the in fetal areas epiteliochorial pig's placenta on day 30 of pregnancy. These structures are located over the opening of the uterine glands. Areolaes consist from maternal and foetal parts. Areola include glandular epithelium, chorial and endometrial stroma at the mouth of the uterine glands, areolar cavity-enhanced formed by endometrial and chorial invaginations. Chorion gives in cavity radial folds lining differences high epithelium. Glycogen, neutral and acid sulfated glycoproteins, proteoglycans, glycosaminoglycans, hyaluronates, total and cationic protein, RNA, arginine, gistidine, lysin were founded in structural components of areoles during gestation period. Numerous areolas serve as specialized sites for absorption the secrets of uterine glands; they are form a powerful functional system of histotrophic nutrition.

Placental expression of vimentin, desmin and ultrastructural changes in the villi in patients with HELLP syndrome

OBJECTIVES

To examine placental expression of vimentin and desmin in relation to ultrastructural changes within the placental villi in cases of HELLP syndrome.

STUDY DESIGN

Formaldehyde-fixed and paraffin-embedded specimens of 15 healthy pregnant and 13 Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome, placentas were used for Harris hematoxylin staining, vimentin and desmin immunohistochemistry, and transmission electron microscopy (TEM).

RESULTS

Increased of fibrinoid necrosis in vascular wall and the periphery of villi were observed in sections of the placentas with HELLP syndrome. Increased expression of vimentin in the intravillous area and increased expression of desmin on blood vessel wall, were seen in placentas of patients with HELLP syndrome when compared to placentas of healthy pregnant.

CONCLUSIONS

Augmentation of intermediate filaments, desmin, vimentin may disturb normal movements of endothelial cells, and may display placental dysfunction that is unable to compensate the endothelial instability and the related hypertension in HELLP syndrome. Further studies are needed to get more definit results and also to compare HELLP syndrome with preeclampsia.

Angiogenesis in villous chorangiosis observed by ultrastructural studies

Chorangiosis is microscopically designated as more than ten terminal capillaries within the villous stroma of the placenta and is mostly related to chronic fetal hypoxia. However, the histogenetic relationship between increased number of terminal villous capillaries and chronic hypoxia has not yet been clarified. Of 665 placentas histologically examined at Saitama Medical University from 2003 to 2010, chorangiosis was found in 58 cases (8.7 %), which were mostly more than 35 gestational weeks. In addition, low birth weight (less than 2,500 g) infants (74.1 %) and those who suffered from cardiac anomalies, chromosome anomalies, and single umbilical artery comprised 32.7 % of cases. Placental lesions were associated with chorangiosis involved in infarct (46.6 %), intervillous thrombosis (20.7 %), and marginal hemorrhages (22.4 %). Scanning electron microscopic studies showed narrowing of vessel ostium and disorders of endothelium in the umbilical cord vessel complicated by chorangiosis. Furthermore, in transmission electron microscopic observation, not only the chorionic villi had multiple enlarged vessels within the villous stroma, but we also found that new capillaries were formed by angiogenesis with endothelial cells derived from fibroblasts under the chronic hypoxic state.

CD34 expression of chorionic villous in pre-eclamptic placenta: an immunohistochemical and ultrastructural study

In this study, pre-eclampsia, proteinuria, and edema associated with hypertension in pregnancy were assessed at the Dicle University School of Medicine Department of Obstetrics and Gynecology Clinic. One group included 20 pre-eclamptic pregnant women with gestational age 20-35 weeks of pregnancy and the same in the control group that included; however, 20 normotensive pregnant women. Histochemistry, immunohistochemistry, and electron microscopy techniques were used. Histopathological examination of syncytial nodes and stromal cells were observed in the increase in hyperplasia and hyalinization. The evaluation immunohistochemical of chorionic villi, placenta, and hematopoietic stem cell markers showed a positive reaction with CD34. Ultrastructural examination showed endoplasmic reticulum dilatation, degeneration of mitochondria in endothelial cells, and capillary vessel edema.

Diabetic placenta: ultrastructure and morphometry of the term villi

OBJECTIVE

To verify the ultrafine conformation of term villi in diabetic and normal placentae. Villar dysmaturity and chorangiosis are considered the most frequent findings in diabetic placentae, but their histogenesis is still unclear.

STUDY DESIGN

We performed a morphometric study of 38 term villi in 5 diabetic placentae and of 37 term villi of 5 normal placentae in order to know the different extension of endothelial surface (VL), the maximum (D max) and minimum (D min) distance of the vessels from the basal membrane, as well as the exact thickness of basal membrane (MT BM). The villi were examined with transmission electron microscopy, and parameters were automatically acquired with the iTEM software (Soft Imaging System, Münster, Germany).

RESULTS

VL results were statistically higher in diabetic placentae than in normal ones. Also D max and D min were higher in diabetic disease. MT BM was not different in the two groups.

CONCLUSION

Our findings show that, in the presence of chorangiosis, the vessel surface in diabetic placentae is higher than in normal group, but the vessels are randomly distributed in term villi. The basal membrane is not different in the two groups. Morphometric evaluation seems to be more accurate using ultrafine samples.

[Human placenta structure in II and III trimesters of physiological pregnancy]

The placenta of 20 women with normal pregnancy was studied during II and III trimesters to obtain the complex characteristic of the structures participating in the formation of syncytio-capillary membranes. Immunocytochemical endothelial cell marker CD34 and morphometry were used for the assessment of some villous parameters: villous area, villous stromal area, villous epithelial area and vascular endothelium area. The main attention was given to the remodeling of the villous epithelium and capillary network. The significant reduction of the epithelial area and that of the villous stroma was detected simultaneously with intensive their vascularization. Morpho-functionally, most of the terminal villi were specialized, containing sinusoid-type capillaries which were in close contact with attenuated, anuclea regions of syncytiotrophoblast. The proportion of terminal villous endothelium in respect to the stroma was significantly increased. Thus, in II and III trimesters of physiological pregnancy the structural changes take place in the placenta, in particular, the capillaries are transformed into thin-walled sinusoids, that approach and closely interact with syncytiotrophoblast resulting in the formation of the syncytio-capillary membranes necessary for an adequate diffusion and meeting the growing needs of the fetus.

Histomorphometric characteristics of first trimester chorionic villi in pregnancies with low serum pregnancy-associated plasma protein-A levels: relationship with placental three-dimensional power doppler ultrasonographic vascularization

OBJECTIVE

To evaluate histomorphometric vascular characteristics from samples obtained by chorionic villus sampling (CVS) in pregnancies with low serum pregnancy-associated plasma protein-A (PAPP-A) levels and to relate these findings to three-dimensional (3D) placental volume and power Doppler vascularization.

METHODS

Immediately before CVS, placental 3D-power Doppler ultrasonography was performed at 11 + 0 to 13 + 6 weeks in 12 pregnancies with PAPP-A concentrations <0.3 multiples of median (MoM) as well as in 11 control women. Using a standardized setting placental volume, vascularization index (VI), flow index (FI), and vascularization flow index (VFI) were measured. Histomorphometric parameters of villi were blindly evaluated with a video-computerized-image-analysis system.

RESULTS

Pregnancies with low PAPP-A showed a significantly reduced number of capillary vessels per villus cross-section (p = 0.005) and a smaller capillary diameter (p = 0.041). Placental vascular indices were significantly related to the number of fetal capillary vessels per villus (VI: r = 0.51, p = 0.03; FI: r = 0.48, p = 0.04; VFI: r = 0.56, p = 0.01).

CONCLUSIONS

Differences in placental vascularization are present in first trimester in pregnancies with low PAPP-A and they are associated to altered 3D placental Doppler indices.

Chorionic villi ultrastructure in the prenatal diagnosis of glycogenosis type II

OBJECTIVE

To perform the ultrastructural examination of a chorionic villi biopsy as a predictor of foetal involvement in the infantile form of glycogenosis type II (Pompe disease).

METHODS

Ultrastructural, biochemical and genetic analyses were performed on chorionic villi biopsies of three consecutive pregnancies in a woman with a previous child affected by Pompe disease.

RESULTS

In the only affected foetus, glycogen storage was observed in fibrocytes and endothelial cells of a chorionic villi sample at 11 week's gestation. Severe multi-organ involvement was demonstrated in the tissues of the aborted foetus. No abnormal material was found in the chorionic samples of two subsequent pregnancies, and a healthy boy and girl were born at term and remain unaffected. Both exhibited a partial reduction in acid maltase and were carriers of the maternal mutation.

CONCLUSIONS

Ultrastructural findings correlated with biochemical and genetic results, providing a clear and early indicator of the definite diagnosis for future pregnancy management or an early therapeutic approach.

[Ultrastructural aspects of the HIV-1 infection in human placental villi with zidovudine treatment]

BACKGROUND

HIV patients with normal placental villi can suffer degenerative changes, the hormones that maintain pregnancy (HCG and progesterone) are diminishing, the pH of blood and oxygen tensions lower.

OBJECTIVE

To demonstrate ultrastructural degenerative changes in placental villi at term of pregnant women infected by HIV-1 with zidovudine treatment.

MATERIAL AND METHOD

Four placentas at term from seropositive mothers were analyzed; three specimens of each one were processed with conventional transmission electron microscopy. The results were compared with four control cases.

RESULTS

Particles belonging to the viral structure associated with the microvilli of the syncytium and cytoplasmic regions were found. Were observed: interruptions of syncytial plasma membrane, syncytial edema; loss of ribosomes at level of RER, disappearance of mitochondria, Golgi complex, RER, lysosomes and cytoplasmic filaments, dissolution of hyaloplasmic matrix, filopodiums of syncytial membrane, aggregated nuclear heterochromatin and dilated perinuclear cistern. Macrophagues had numerous particles into cytoplasm, probably pertaining to electron dense material contained in the viral nucleocapsid, also observed in the stromal region close to the endothelium of the villus. Some myofibroblasts were detected suffering a process of cellular death with cariorexis event.

CONCLUSIONS

These changes indicate that the cytopathic effect spreads from peripheral syncytium to stromal zone suggesting that the damaged placental barrier don't have the better conditions for the transmission of gases, nutrients and metabolites toward fetal circulation.

Placenta and umbilical cord blood deserve attention

OBJECTIVES

This work follows up with our already published results concerning consequences of lead on prenatal and postnatal development of child in connection with the rise of hyperkinetic syndrome (ADHD). This disease has in children increasing tendency all over the world.

METHODS

In our work we used a set of histological and histochemical methods, method of scanning electron microscopy, infrared spectroscopy and statistical evaluation.

RESULTS

Our new method for proof of lead in placenta enabled us to show how lead is cumulated in syncytiotrophoblast. We have found release of lead from mother's erythrocytes in the intervillous space and receipt of lead by erythrocytes of fetus in the vessels of the villi of placenta. This finding enriches knowledge about relation between mother's erythrocytes, lead, calcium that is lead carrier, syncytiotrophoblast, and erythrocytes of fetus in the vessels of placental villi. We have proved that syncytiotrophoblast is the most frequent place for cumulation of lead deposits. We verified our ecomorphologic results by means of infrared spectroscopy in cooperation with physicists and statistically evaluated occurrence of ADHD in particular age categories what helps to fill gaps in knowledge of ADHD etiology.

CONCLUSIONS

Our finding of lead in umbilical cord blood immediately after the child birth is forewarning against the possible rise of the ADHD. This finding facilitates early diagnostics and means preventing step against the rise, development and consequences of this disease. The obtained results give evidence about the serious influence of mother's dwelling in environment polluted with neurotoxic metal - lead on the prenatal and postnatal development of child.

Electron Microscopy of Chorionic Villus Samples for Prenatal Diagnosis of Lysosomal Storage Disorders

Some lysosomal storage disorders cause progressive prenatal accumulation of undegradable metabolites that manifest as membrane-bound vacuoles in endothelial cells, fibroblasts, and trophoblast, identifiable by electron microscopic examination of chorionic villus samples (CVS). There were 111 CVS, which had ultrastructural examination for suspected storage disorders at Great Ormond Street Hospital (1988-2005). There were 31 positive diagnoses, including glycogen storage disease type II, gangliosidosis type 1, mucopolysaccharidosis type 1, MPS not specified, Niemann-Pick type A, sialidosis/mucolipidosis type 1, neuronal ceroid lipofuscinoses (including variant forms), Wolman disease, sialic acid storage disease, and storage disease not specified. In most of these cases the indication was a previously affected individual. Seventy-seven cases showed no evidence of storage disease; 3 samples were inadequate for ultrastructural diagnosis. In selected cases, one-third of CVS may demonstrate distinctive ultrastructural features allowing prenatal diagnosis of a range of storage diseases.

Placentation in the Hottentot golden mole, Amblysomus hottentotus (Afrosoricida: Chrysochloridae)

The placentation of the Hottentot golden mole (Amblysomus hottentotus) has been examined using light and electron microscopy and lectin histochemistry of nine specimens at both mid and late gestation. The placentae were lobulated towards the allantoic surface and the lobules contained roughly parallel arrays of labyrinthine structures converging on a central spongy zone. At mid gestation, the arrays were composed of an inner cellular and outer syncytial trophoblast layer, the inner layer enclosing scant connective tissue and fetal capillaries. Maternal blood spaces coursed through the outer trophoblast and were lined by trophoblastic microvilli; the blood spaces were narrow in mid gestation but enlarged near term, while the inner trophoblast layer became thinner and seemed to be syncytial. These features were confirmed by transmission electron microscopy. The microvillous surfaces and dispersed cytoplasmic particles were heavily glycosylated, as shown by lectin histochemistry, and exhibited changes with maturation, particularly a loss in N-acetyl glucosamine oligomers bound by Phytolacca americana lectin on the microvilli lining the maternal blood spaces and outer trophoblast particles. A substantial yolk sac was present both in mid and late gestation stages. It was clearly unattached to the uterus in the later stages. These morphological features are discussed in relation to the phylogenetic position of Amblysomus with respect to other members of Afrosoricida and Afrotheria.

Fluorescence intensity profiles of in situ hybridization signals depict genome architecture within human interphase nuclei

An approach towards construction of two-dimensional (2D) and three-dimensional (3D) profiles of interphase chromatin architecture by quantification of fluorescence in situ hybridization (FISH) signal intensity is proposed. The technique was applied for analysis of signal intensity and distribution within interphase nuclei of somatic cells in different human tissues. Whole genomic DNA, fraction of repeated DNA sequences (Cot 1) and cloned satellite DNA were used as probes for FISH. The 2D and 3D fluorescence intensity profiles were able to depict FISH signal associations and somatic chromosome pairing. Furthermore, it allowed the detection of replicating signal patterns, the assessment of hybridization efficiency, and comparative analysis of DNA content variation of specific heterochromatic chromosomal regions. The 3D fluorescence intensity profiles allowed the analysis of intensity gradient within the signal volume. An approach was found applicable for determination of assembly of different types of DNA sequences, including classical satellite and alphoid DNA, gene-rich (G-negative bands) and gene-poor (G-positive bands) chromosomal regions as well as for assessment of chromatin architecture and targeted DNA sequence distribution within interphase nuclei. We conclude the approach to be a powerful additional tool for analysis of interphase genome architecture and chromosome behavior in the nucleus of human somatic cells.

The Role of heat shock protein 27 in extravillous trophoblast differentiation

Trophoblast cells from placental explants differentiate in culture to extravillous trophoblast cells (EVT cells). During trophoblast differentiation heat-shock-protein-27 (HSP27) mRNA and multidrug-resistance-protein-5 (MRP5, transporter of cyclic nucleotides) expression are increased. HSP27 is a regulator of actin filaments structure and dynamic, has a role in cell differentiation and may affect NF-kB activity. In this study we aimed to assess HSP27 level in trophoblast cells and its correlation with motility and differentiation related processes [MMPs activity, nitric oxide (NO), inducible nitric oxide synthase (iNOS), proliferation and MRP5 levels]. We evaluated HSP27 expression in a first trimester human trophoblast explants model designed to assess EVT cells differentiation/migration with/without 6-mercaptopurine (6MP, an EVT inhibitor of migration). We found that HSP27 level is expressed in the nucleous and cytoplasm of non-proliferting villous-trophoblast cells (negative for Ki67) and in the cell periphery and cytoplasm of motile EVT cells. Moreover, 6MP decreased HSP27 nucleous expression that was associated with inhibited MMP2 activity and NO production. Also decreased iNOS expression and increased MRP5 mRNA levels were observed. In conclusion, HSP27 expression is modulated in concordance with migration dependent parameters in trophoblast cells.

[Incidence of gestational trophoblastic disease detected by routine histopathologic study of specimens obtained from abortions]

BACKGROUND

Gestational trophoblastic disease (GTD) comprises different types of placental changes distinguished by histologic hydropic degeneration and swelling of chorionic villi.

OBJECTIVE

To report incidence of gestational trophoblastic disease in a general hospital.

MATERIAL AND METHODS

A cross-sectional study in the period of January 2000 to June 2006 was made. Histopathologic report of specimen abortion with gestational trophoblastic disease was registered and we calculated the incidence of births, abortions and total pregnancies.

RESULTS

In the study period, 142 cases of gestational trophoblastic disease were registered, and an incidence of 1:243 births and 1:31 abortions (1:274 pregnancies) was found. The average age of patients was 27.1 years (15 to 50), 67% of the cases were not clinically suspected.

CONCLUSIONS

Histopathologic study of specimen abortions allows calculating precisely incidence of gestational trophoblastic disease, but the findings of this study may be different because numerators and denominators used in the calculation are not the same.

Cellular diversity of human placental stem villi: an ultrastructural and immunohistochemical study

The aim of the study was to investigate the distribution and differentiation of cell types in the stroma of human placental stem villi (SV). A total of 14 human term placental tissues were studied. Double immunolabeling was performed for desmin-vimentin, desmin-alpha-smooth actin and vimentin-alpha-smooth actin. Cytokeratin 7, proliferating cell nuclear antigen immunolabeling was also performed. Parallel tissue samples were examined by transmission electron microscopy. HSCORE was performed for the semi-quantitative analysis of distribution of cells in the stroma of SV. Vimentin-labeled cells were mostly distributed in the subtrophoblastic area. Desmin-vimentin double immunolabeling was mainly localized in the triangular area and to a lesser degree in the perivascular area and vessel walls (p=or<0.001). However, desmin-alpha smooth actin labeling was observed predominantly in the vessel wall and perivascular area. Vimentin-alpha smooth actin immunoreactivity was significantly stronger in the triangular and perivascular areas compared to the vessel walls (p=0.003). Ultrastructurally, cells in the stroma of SV were mesenchyme cells, reticulum cells, fibroblasts, myofibroblasts, smooth muscle cells, and Hofbauer cells, filamented and vacuolated cells. The differentiation of myofibroblasts in the triangular and perivascular areas may play a role in maturation of SV and villous contractility, modulation of the intervillous space and this may have effects on maternofetal placental circulation.

Occurrence of lead in placenta--important information for prenatal and postnatal development of child

This work points out consequences of lead on prenatal and postnatal development of child that have not been elaborated in such extent before. Our new method for proof of lead in placenta enabled us to show how lead is from mother's blood erythrocytes in the intervillous space released and received by the villous syncytiotrophoblast. This finding enriches relation between mother's erythrocytes, lead, calcium that is a lead carrier, and syncytiotrophoblast. Our finding of abundant thin terminal villi, that in some places form bunches observed in scanning electron microscope, points out deficiency of O2 and CO2 transport in placenta. This phenomenon is indirect evidence that periphery "starves" for oxygen that participates in maintaining conditions for intact development of child. Behaviour of fibrin deposit layer before the childbirth is also discussed. Attention is paid to possible rise of hyperkinetic syndrome of children as a consequence of mother's dwelling in environment polluted with lead. Presence of lead is verified by infrared spectroscopy.

Significance of PAM histochemical reaction in delineating macrophages

Periodic acid methenamine silver staining has been used for proof of the existence of carbohydrates in both paraffin and resin embedded tissues. The staining was applied to delineate macrophages that have been well known as cells of mononuclear phagocyte system by stainable nature for lysosomes, and it is found to be useful method for detection of macrophage. Fetal macrophage, which is often observed in placental villi, is called the highly vacuolated cell. Vacuoles in the cytoplasm seem to be empty with light microscopic staining, but it is clarified that they contain a full amount of carbohydrate. The present result leads us to the necessity of reconsidering the functional aspect of fetal macrophage.

Presence of erythrocytes in the villous trophoblast cell layer of normal first trimester and term human placentae

Light and electron microscopic examination of first-trimester and term human placental tissues were performed to identify erythrocytes containing hemoglobin in the villous trophoblast cell layer. Erythrocytes were not identified in chorionic villous epithelium at week 7 of gestation. These cells first appeared in the villous cytotrophoblast at week 8, and continued to be present in the villous cytotrophoblast until week 9, as shown by benzidine staining. At week 12 gestation, a cluster of erythrocytes was present in a villous syncytial sprout. At 40 and 41 weeks gestation, erythrocytes were located in the villous cytotrophoblast cell layer. Electron microscopic observations focused on the cytoplasm of villous cytotrophoblast at week 8, the syncytial sprout at week 12 and the cytotrophoblast cell layer at term, confirmed the presence of erythrocytes at an extravascular location, as observed by light microscopy.

P57kip2 immunohistochemical expression and ultrastructural findings of gestational trophoblastic disease and related disorders

Gestational trophoblastic disease (GTD) is a unique spectrum of diseases ranging from complete hydatidiform mole (CHM), partial hydatidiform mole (PHM), and invasive mole (IM) to choriocarcinoma (CC). Placental site trophoblastic tumor (PSTT) and epithelioid trophoblastic tumor (ETT) have been classified as related disorders. Mesenchymal dysplasia (MD) may be misdiagnosed as PHM; however, it is said to have a quite different histogenesis from PHM. P57kip2 is the protein product of a paternally imprinted or maternal gene that inhibits cyclin-dependent kinases (CDK), thus serving to inhibit cell proliferation and to suppress tumor growth. Its lack of expression in trophoblastic disease plays a role in its abnormal proliferation and differentiation. In this study, P57kip2 immunostaining was absent in the trophoblastic layers of CHM and was positive in the trophoblast layer of nonmolar villi and MD. Ultrastructure of complete molar cystic villi showed tree-like branching of microvillous processes and intracytoplasmic lacunae without capillaries in the stroma, whereas MD contained many newly formed blood vessels and collagen. Also, large lacunae with microvilli and polymorphic nuclei of syncytiotrophoblast cells with well-developed organelles were observed in IM. Lung ETT following CHM and normal deliveries showed two types of large mononuclear cells and binuclear cells with abundant organelles and bundles of intermediate-type filaments in the stroma.

The cytotrophoblast layer of human chorionic villi becomes thinner but maintains its structural integrity during gestation

Chorionic villi in the human placenta serve as essential structures in fetomaternal exchanges. According to the embryology and placentology literature, during the first trimester, the cytotrophoblast (CTB) layer that is subjacent to the syncytiotrophoblast (STB) and supported by a basal lamina is nearly complete, but later, it becomes discontinuous. In the present study, we investigated the structural integrity of the CTB layer in the normal villous tree by advanced microscopy techniques using an antibody to hepatocyte growth factor (HGF) activator inhibitor type 1 (SPINT1), a potent inhibitor of HGF activators expressed exclusively on villous CTB. In full-term placenta, the cell surface of the CTB layer was spread over the basal lamina but was not interrupted. Morphometric analysis showed that throughout the villous tree, 80% of the continuity of the CTB layer of full-term placenta and 90% of that of first-trimester placenta were preserved. Gestation was accompanied by unique structural change in the basal domain of the trophoblast layer. The initially cuboidal-shaped CTB cells were transformed to flat cells with many cellular processes that, together with those of the adjacent STB, eventually covered the trophoblast basal lamina in a complex network of interdigitations. In addition, the expression levels of SPINT1, ST14, HGF, and MET mRNAs in the villous tree increased over the course of gestation. These results suggest that the structural integrity of the SPINT1-positive CTB layer may play an important role in villous differentiation and in maintenance of the villous tree via the HGF signaling system during gestation.

Comparative Placentation: Some Interesting Modifications for Histotrophic Nutrition – A Review

In considering the diversity of Eutherian mammalian placental structure, it is helpful to keep in mind that both phylogenetically and ontogenetically a functional yolk sac placenta precedes development of the chorioallantoic placenta. Usually the chorioallantoic placenta progressively displaces the area of contact of the yolk sac placenta with the endometrium. It is also closely applied to the endometrium, increasing respiratory efficiency but tending to decrease histotrophic nutrition. Catarrhine primates have minimal histotrophic uptake, using haemotrophic mechanisms throughout most of gestation. Rodents, by using partial or complete inversion of the yolk sac, have extensive regions available to histotroph in later pregnancy. Most mammals, however, have developed specialized regions of the chorioallantoic placenta for ingestion of uterine secretions, cell debris and erythrocytes. These regions vary from simple saccular areolae to more complex areolae such as the chorionic vesicles of prosimian primates to specialized haemophagous areas. All such structures are consistently lined by columnar cellular trophoblast. Examples of these structures, many of which can ingest both glandular secretions and erythrocytes (i.e. they are heterophagous), can be found in species whose definitive placenta is epitheliochorial. They are common but not universal in species whose definitive placenta is endotheliochorial and are even found in a few species with definitive haemochorial placentas. Restriction of phagocytosis to regions of columnar cells provides polarized cells appropriately oriented for ingestion, breakdown and transport, and limits the type of ingestion of both beneficial and potentially toxic materials to expendable individual cells.

Contractile cells and fibrillin-1 distribution is disturbed in terminal villi of placentae from patients with preeclampsia and systemic lupus erythematosus

Placentae from patients with preeclampsia (PE) and systemic lupus erythematosus (SLE) present many alterations that may impair materno-fetal exchange. We investigated the distribution of contractile cells and fibrillin-1 in terminal villi of term placentae from patients with PE or SLE and compared to control placentae. Stroma in terminal villi exhibited intense labelling for fibrillin-1. The fibrillin-1 villi surface fraction was greater in PE and SLE placentae than in controls (13+/-0.4%, 14+/-0.5%, 10+/-0.4%; p=0.0001). Immunohistochemistry for alpha-smooth muscle (SM) actin showed few contractile cells in control terminal villi stroma, localized around fetal capillaries and showed rare processes in vasculo-syncytial membrane. PE and SLE placentae exhibited an increase in the number of capillaries presenting alpha-SM actin adventitial positive cells. The presence of alpha-SM actin processes interposed in the vasculo-syncytial membrane was greater in SLE villi than in PE and controls. Ultrastructural observations confirmed in SLE and PE terminal villi the presence of these processes in vasculo-syncytial membrane and also showed a thickened trophoblastic basement membrane. The present study demonstrates that an important myofibroelastic system is present in term terminal villi, and that this system is actively remodelled in PE and SLE placentae.

[Analysis of chromosomal aberrations in the chorionic cells of induced abortions as a method for estimating the level of spontaneous mutagenesis]

Chromosomes were morphologically studied in the chorionic fibroblasts of induced abortions. Chorionic villi biopsy specimens taken during 103 abortions at gestational weeks 6-12 served as a material for this investigation. They were taken from women with pregnancies interrupted due to that there were social indications. Metaphase and prometaphase chromosomal specimens were obtained by the test modified by V. Baranov 4-5 hours after chorionic villi biopsy, without preliminarily tissue cultivation. A cytogenetic analysis revealed an abnormal karyotype in 2.91%. The frequency of chromosomal aberrations may serve as a control for prospective studies of spontaneous mutagenesis in a region and the chorion of induced abortion may be regarded as a test unit of mutagenic and embryotoxic effects on the fetus.

[Molecular-cytogenetic study of the aborted fetuses in women with reproductive function disorders]

It is known that the frequency of chromosomal abnormalities among spontaneous miscarriages of the first trimester of pregnancy makes 50-60%. Research of karyotypes of chorionic villus cells of miscarriages has been conducted by combining the standard cytogenetic method and the FISH analysis on interphase nuclei of centromeric specific DNA samples by the tests to the chromosomes 13/21, 14/22, 15, 16, 18, X, Y. The described complex approach can be successfully applied for effective identification ofchromosomal abnormalities in the material of spontaneous miscarriages. The results specify the necessity of careful study of genomes of matrimonial pairs with the usual unmaturing in anamnesis and especially before treatment by IVF methods.

Comparative genomic hybridization analysis of spontaneous abortion

OBJECTIVES

To evaluate the feasibility and superiority of comparative genomic hybridization (CGH) in the genetic analysis of spontaneously aborted tissues.

METHODS

38 conceptuses from early failed pregnancies were studied, of which, 27 samples were fresh and 11 were old. Each sample was divided into two parts, one part for conventional cytogenetic analysis and the other for CGH analysis.

RESULTS

All 38 spontaneously aborted tissues were analyzed successfully by the CGH approach, but only 31 samples received results from the cytogenetic karyotype analysis, while 7 other tissues failed to get data due to failure in tissue culturing. Among the specimen successfully analyzed by both approaches, 90% (28 out of 31) obtained identical results, and 14 aneuploidies were found. The only structural chromosome aberration in this series, 46, XY, del(3) (q22-24), was found using the CGH approach, which appeared as a normal male karyotype on the chromosomal metaphase spread. Also, two cases indicated triploidies under cytogenetic analysis but appeared to be normal on the CGH profile. In addition, among the seven samples of tissue culture failure, CGH identified three to be aneuploidies.

CONCLUSION

The CGH analysis accurately identifies chromosomal unbalanced abnormalities related to spontaneous abortions with low failure rate.

Immortalization of human extravillous cytotrophoblasts by human papilloma virus gene E6E7: sequential cytogenetic and molecular genetic characterization

Extravillous cytotrophoblast (EVCT) cultures from the normal placentas of three pregnant women were transfected by HPVE6E7. Sequential cytogenetic and molecular analyses were performed to delineate genetic events that may be critical for cell immortalization. One line, PE1-E6E7, was immortalized successfully, whereas 2 other lines, PE3-E6E7 and PE4-E6E7, could not be maintained beyond crisis. Before crisis, the majority of cells in all lines were karyotypically normal. During the early stages of crisis, there was progressive telomere shortening. Most cells were karyotypically abnormal, with extreme cytogenetic divergence and a predominance of telomeric association and dicentric chromosomes affecting many chromosomes. At the later stages of crisis, the karyotype became more convergent with a drastic decrease in nonclonal aberrations. In PE1-E6E7, after crisis the karyotype was complex, with frequent centromeric rearrangements in the form of isochromosomes and whole-arm translocations. There were unbalanced structural aberrations and numerical changes, including loss of chromosome 13, that could be traced throughout the evolution of the line. These findings support the concept that immortalization is a relatively rare and nonrandom event that occurs only in cells that have acquired the necessary or critical genetic alterations. Telomeric dysfunction may be an important mechanism leading to the acquisition of complex karyotypical aberrations.

Ultrastructure of the chorioallantoic placenta and chorionic vesicles of the lesser bush baby (Galago senegalensis)

The ultrastructure of the chorioallantoic placenta of the lesser bush baby (Galago senegalensis) has been studied. The placenta was shown to be of the diffuse, epitheliochorial and adeciduate type. The trophoblasts of the chorionic villi, other than those lining the chorionic vesicles, were characterized by the presence of many lipid droplets. In the later stage of gestation, the fetal capillaries indented the trophoblastic epithelium reducing the distance between fetal and maternal circulations. In addition chorionic vesicles were observed. The trophoblasts lining the chorionic vesicles have outward bulging apical surfaces. There are clefts between these cells and this region is occupied by microvilli of adjacent cells. Several layers of fusiform cells that did not extend up into the cores of the chorionic vesicle villi formed the outer component of the vesicular wall. Granulated cells were observed within the maternal connective tissue and their possible role is discussed.

Expression of variant luteinizing hormone/chorionic gonadotropin receptors and degradation of chorionic gonadotropin in human chorionic villous macrophages

Human gonads and non-gonadal organs/tissues express luteinizing hormone/chorionic gonadotropin (LH/CG) receptors. This study aimed to identify the LH/CG receptors and to clarify their function in human placental chorionic villous macrophages. Macrophages as well as syncytiotrophoblasts of human chorionic villous tissues were immunohistochemically positive for LH/CG receptor throughout gestation. By reverse transcription-nested polymerase chain reaction methods, villous macrophages were shown to express a variant type of LH/CG receptor, the sequencing of which revealed a deletion of exon 9. For experiments in vitro, a monocyte-macrophage cell line, THP-1, was transfected with vector alone, wild-type LH/CG receptor, and exon 9-deleted LH/CG receptor after phorbol 12-myristate 13-acetate (PMA) treatment. Non-PMA-treated THP-1 cells transfected with vector alone were also examined. THP-1 cells expressed exon 9-deleted LH/CG receptor after treatment with PMA. After the cells of the four groups were cultured in medium containing intact human CG (hCG), the concentrations of hCG and its beta-core fragment (beta-CF) were measured in the supernatant of the culture medium and in the cell cytosol. Time-dependent hCG uptake was observed in both non-PMA-treated and PMA-treated THP-1 cells, suggesting that the variant receptor is not directly involved in the ingestion of hCG. The degradation of hCG and excretion of beta-CF were progressed in PMA-treated cells but not in the un-treated cells. In the cell cytosol, the ratio of beta-CF and hCG concentrations (beta-CF/hCG) was significantly higher in the PMA-treated cells than in non-PMA-treated cells; however, it did not differ between the PMA-treated cells transfected with exon 9-deleted receptor and those transfected with vector alone. Macrophages may express the variant receptor in order to recognize the intracytoplasmic hCG and transport it to the lysosome. Among the two PMA-treated cells, the ratio was lower in those transfected with wild-type receptor. The expression of the variant receptor may modulate the degradation of hCG but be reduced by expression of the wild-type receptor in its lacking macrophages. Our data suggest a potentially important role for exon 9-deleted LH/CG receptors expressed in human placental villous macrophages in the local metabolism of hCG.

A Novel FcγR-Defined, IgG-Containing Organelle in Placental Endothelium

Placental transfer of IgG from maternal circulation to that of the fetus is crucial for fetal and newborn immunity. This process requires that IgG broach two cellular layers of the placenta. IgG transport across the first layer, the syncytiotrophoblast, is almost certainly mediated by the MHC-related FcR for IgG, FcRn. The second layer, the villus endothelium, was until recently thought to allow IgG movement nonspecifically by constitutive transcytosis in caveolae. However, we recently showed that villus endothelium expressed a separate FcR for IgG, the inhibitory motif-bearing Fc gammaRIIb2 seen most notably on macrophages and as a minor fraction of the Fc gammaRIIb expressed on B cells. Now, by quantitative microscopy, we find Fc gammaRIIb2 to be expressed abundantly in an unidentifiable and likely novel organelle of the villus endothelium, unassociated with caveolae. About half of these Fc gammaRIIb2 organelles contain IgG; the remainder lack IgG. The majority fraction (approximately 80%) of IgG-containing organelles is associated with Fc gammaRIIb. No IgG-containing organelles are associated with caveolin. These findings are compatible with Fc gammaRIIb-mediated transfer of IgG across the villus endothelium, independent of caveolae.

Characteristics of histopathological and ultrastructural features of placental villi in pregnant Nepalese women

The placenta is an important functional unit for gas transfer between mother and fetus. The placental membrane, consisting of trophoblast layer interposed between maternal and fetal blood, plays an active role for intensity of respiration, but no morphological evidence has been documented. Until now, it has been reported that fetal growth retardation and increased fetal mortality rate usually could be seen at high altitude. In an attempt to find the cause of high perinatal mortality rate in Nepal, this study was undertaken to examine pathologically about 1000 Himalayan placentas obtained in Nepal and Tibet since 1977, and the results were compared with those of 5500 Japanese placentas at Saitama Medical School since 1990. In this study, characteristics of ultrastructural features of the Nepalese placental villi investigated in recent years are reported. (1) The gross characteristics of placental pathology in the Himalayan group were represented by marked subchorionic fibrin deposits and increased chorionic cysts in contrast to low incidence of intervillous thrombosis compared with those of the Japanese group. (2) As characteristics of histological findings of the placental villi between Himalayan and Japanese groups, the incidence of chorangiosis and chorangioma in the Himalayan group was significantly higher than that in the Japanese group. (3) Accompanying an increase of vasculosyncytial membrane (VSM) in the villi, thickness and separation of basement membrane of the syncytium in addition to increased apoptosis of syncytial cell nuclei were recognized. (4) As characteristic ultrastructural features of chorionic villi of Nepalese placentas, an increase of mitochondria and cystic formation of rough endoplasmic reticulum (rER), in addition to appearance of lamellar bodies similar to alveolar epithelial type II cell in organellae of the syncytium, were observed. These ultrastructural changes of the placental villous capillaries may be ascribed to hypervascularization caused by the chronic hypoxic state. It is, therefore, presumed that trophoblast cells may play an important role for gas transfer mechanism under such a hypoxic state at high altitude.

[Study on the presence of hepatitis B virus in first-trimester villi in pregnant women with hepatitis B surface antigen positive]

OBJECTIVE

To observe the presence of hepatitis B virus (HBV) in first-trimester villi cells from pregnant women carrying HBsAg.

METHODS

Immunohistochemical streptavidin-biotin peroxidase complex (SABC) staining with monoclonal HBsAg, hepatitis B core antigen (HBcAg) and PCR, in situ hybridization were used for detection of HBV infection markers in villi. Positive villi ultramicrostructures were observed with transmission electron microscope.

RESULTS

HBV was detected in 8 of 25 villi of HBsAg positive pregnant women, the positive rate was 32%. HBsAg was located in the decidual cell, trophoblastic cell and villous mesenchymal cell. HBV analog was detected in rough endoplasmic reticulum of trophoblastic cell.

CONCLUSIONS

HBV may infect villous cells in first-trimester pregnancy. It would be impossible for HBV to transmit the desmosomes.

[The role placental factors in formation of perinatal pathology in gestosis of different severity]

Morphological study of gestosis in 153 cases. In light degree of gestosis focal ishemic and hemorrhagic infarcti and vascular changes of villi are found; decrease of the size of intervillous space at moderate degree and the 2nd stage of chronical placental hypertension. Hypoplasia of placentas, umbilical cord pathology and chronical placental hypertension in gestosis of a grave degree.

[Morphological peculiarities of terminal placental villi in Capreolus capreolus pygargus]

This investigation was aimed at the study of peculiarities of placentation in Siberian roe (Capreolus capreolus pygargus)--one of the representatives of the Cervidae family which is characterized by an embryonic diapause. Using histological and morphometric methods, the main structural-functional regularities of the organization of roe placenta were determined at different stages of gestation, that included the formation of placenta at later stages of gestation, as compared with other ruminants, prevalence of trophoblastic lining over the connective tissue in terminal villi in the zone of intensive exchange between mother and fetus up to the 5th month of gestation, high degree of capillarity of terminal villi, high numerical density of giant cells in trophoblast. The problems of trophoblast regeneration in the terminal villi and an adaptational role of embryonic diapause in fetal survival and maintenance of vital functions, are discussed.

Cytoplasmic microvesicular form of Fas ligand in human early placenta: switching the tissue immune privilege hypothesis from cellular to vesicular level

The local immune privilege of the fetus is created by the placenta. Fas ligand (FasL) expression in trophoblast has been implied as one of the mechanisms of fetal tolerance. However, the expression of membranal FasL by trophoblast has failed to explain this role of FasL. Two objections can be raised: (1) there have been contradictions considering which trophoblast cells, syncytiotrophoblast (ST) or cytotrophoblast, express FasL; (2) in vivo and in vitro studies have shown that the membranal form of FasL evokes inflammatory response and thus may promote fetal rejection. Using different assays and the FasL-specific antibody G247-4 we demonstrate beyond doubt that in vivo, (1) FasL is produced by and stored in the first trimester human ST only and (2) the human ST lacks surface membranal FasL. Instead, FasL, loaded in microvesicles, is stored in cytoplasmic granules. These results complement the recent in vitro studies of the microvesicular form of FasL secretion by cultured trophoblast cells, and suggest that placental FasL is synthesized by villous ST, stored in microvesicular form and secreted as exosomes. Secretion of the exosome-associated form of FasL may be one mechanism by which the placenta promotes a state of immune privilege. Additionally, FasL expression in Hofbauer cells is also demonstrated.

Growth factors and their receptors: fundamental molecules for human placental development

In this review we present data concerning the localization of some important growth factors and their receptors in the human placenta. We focus our attention on molecules playing a fundamental role in angiogenesis and morphologic processes as beta-FGF, EGF and TGF-beta. The distribution of these growth factors and their receptors in the placental villi during gestation suggests that these molecules play a pivotal role in growth and differentiation of the villous tree.

A comparative study of the effect of three different syncytiotrophoblast micro-particles preparations on endothelial cells

Pre-eclampsia is a pregnancy-associated multi-system disorder of unknown etiology, characterized by damage to the maternal endothelium. The latter facet has been suggested to be mediated in part by elevated shedding of inflammatory placental syncytiotrophoblast micro-particles (STBM) into the maternal circulation. In this study, we have examined STBM prepared by three different methods: mechanical dissection, in vitro placental explant culture and perfusion of placental cotyledons. All three preparations yielded morphologically similar STBM, as confirmed by scanning electron microscopy, and all contained syncytiotrophoblast-specific proteins as determined by the presence of placental alkaline phosphatase. The functional properties of the three STBM preparations were examined on human umbilical vein endothelial cells (HUVEC), where the mechanically prepared particles were found to inhibit proliferation to the greatest extent. Furthermore, only mechanically prepared STBM lead to the detachment and apoptosis of HUVEC cells. Our study, therefore, suggests that STBM prepared from placental perfusion or in vitro explant culture are biologically different from mechanically prepared ones, and may provide a better approximation of physiologically produced placental micro-particles.

Placental glycosylation in peccary species and its relation to that of swine and dromedary

Comparison has been made between glycans at the fetomaternal interface of two Tayassu species (New World peccaries or wild pigs) and those of swine (true pigs) and dromedary, which have similar epitheliochorial placentae. Plastic sections of near-term fetomaternal interface from Tayassu tajacu (120 days gestation) and Tayassu pecari (140 days gestation) were stained with 20 lectins and compared with those of swine (109 days) and dromedary (375 days). Both Tayassu species showed similar staining characteristics, which differed only slightly from those of the swine. Most differences were quantitative rather than qualitative, except for binding of Arachis hypogaea lectin to terminal beta-galactose which was absent in swine uterine epithelium though present in both Tayassu species, and binding of Sambucus nigra lectin to sialic acid which was absent in swine epithelium and trophoblast though present in Tayassu. Glycosylation of the dromedary fetomaternal interface showed, in contrast, significant differences compared to Tayassu and swine, particularly regarding fucosyl, sialyl and terminal galactosyl residues. Despite a divergence of between 33 million and 37 million years between true pigs and peccaries, glycosylation of the fetomaternal interface has remained similar, with most of the observed changes affecting terminal structures. The dromedary has an epitheliochorial placenta with a similar architecture, but different glycan expression, suggesting modification of glycosyl transferases with evolution. These data contain clues to changes of glycosyl transferase activity that accompany speciation.

Hormonal regulation of glucose and system A amino acid transport in first trimester placental villous fragments

Alterations in placental nutrient transfer have been implicated in fetal growth abnormalities. In pregnancies complicated by diabetes and accelerated fetal growth, upregulations of glucose transporter 1 (GLUT1) and amino acid transporter system A have been shown in the syncytiotrophoblast of term placenta. In contrast, intrauterine growth restriction is associated with a downregulation of placental system A transporters. However, underlying mechanisms of transporter regulation are poorly understood, particularly in early pregnancy. In this study, hormonal regulation of placental glucose and system A transporters was investigated. The uptake of 3-O-[methyl-(14)C]-d-glucose was studied in villous fragments isolated from first trimester (6-13 wk of gestation) and term human placenta. Villous fragments were incubated in buffer containing insulin, leptin, cortisol, growth hormone (GH), prolactin, IGF-I, or under hypo/hyperglycemic conditions for 1 h. Subsequently, 3-O-[methyl-(14)C]-D-glucose uptake was measured with and without phloretin for 70 s in first trimester tissue and 20 s in term tissue. Methylaminoisobutyric uptake was measured with and without Na+ for 20 min. Glucose uptake was unaltered by hormones or hypo/hyperglycemia. GH decreased system A activity by 31% in first trimester (P < 0.05). The uptake of glucose was 50% higher in term compared with first trimester fragments and increased markedly between 6 and 13 wk of gestation (P < 0.05). We conclude that placental glucose transporter activity is not regulated by short exposures to the hormones or glucose concentrations tested. In contrast to term placental villous fragments, system A activity was not regulated by insulin or leptin in first trimester but was downregulated by GH.

The protein C system in placental massive perivillous fibrin deposition

Massive perivillous fibrin deposition (MPFD) is associated with intrauterine growth retardation and first-trimester and second-trimester spontaneous abortion. Histologically, villi near the maternal interface are completely surrounded by fibrinoid material. This work compared the expression of thrombomodulin (TM) and endothelial protein C receptor (EPCR) in early miscarriage specimens with and without MPFD. Ten specimens with a gestational age of 7-12 weeks (mean 10 weeks) and 10 age-matched miscarriage specimens lacking MPFD were sampled. Formalin-fixed paraffin-embedded sections were stained with monoclonal antibodies against TM and EPCR using an immunoperoxidase method. The slides were independently reviewed by two pathologists using a semiquantitative grading system. Among unaffected villi, there was no difference in staining for TM or EPCR in cases of massive perivillous fibrin deposition compared with the control group. In the MPFD cases, loss of membrane positivity was noted for both TM and EPCR at the junction between normal villous epithelium and villous epithelium with deposition of fibrin. This could imply an underlying defect of trophoblastic protein C activation. Alternatively, it may represent a degenerative change secondary to impedence of oxygen and nutrient supply to the trophoblastic epithelium.

Disruption of oxygen-regulated responses underlies pathological changes in the placentas of women who smoke or who are passively exposed to smoke during pregnancy

Previously, we showed that maternal smoking harms human placental development by changing the balance between cytotrophoblast (CTB) proliferation and differentiation. To understand the mechanisms involved, we studied the effects of maternal smoking and in vitro exposure of CTBs to nicotine and on CTB expression of molecules that govern cellular responses to oxygen tension: the von Hippel-Lindau tumor suppressor protein (pVHL), the hypoxia-inducible transcription factors (HIFs), and the vascular endothelial growth factors (VEGFs). We previously reported that hypoxia upregulates CTB pVHL expression (1). Here we show that in vitro exposure of CTBs to nicotine has the same effect. Maternal smoking also dysregulated CTB expression of all three molecules. Remarkably, we found that passive exposure to cigarette smoke had many of the same effects as active smoking, a graphic demonstration of the ill effects of cigarette smoke, even secondhand, on placental development. Together, these findings explain, in part, how smoking damages the placenta by altering expression of key mediators of placental development.

Sequential Expression of VEGF and its Receptors in Human Placental Villi During Very Early Pregnancy: Differences Between Placental Vasculogenesis and Angiogenesis

Vascularization within the human placenta is the result of the de novo formation of vessels derived from pluripotent precursor cells in the mesenchymal core of the villi. Vascularization of placental villi starts at around day 21 post conception (p.c.) with a four somite embryo. At this stage progenitors of haemangiogenic cells differentiate to form first vessels. These progenitor cells are thought to be directly derived from mesenchymal cells rather than originating from fetal blood cells. We investigated the relation between differentiation of stromal cells towards endothelial cells and vascular structures and the expression pattern of the respective growth factors. Using transmission electron microscopy and immunohistochemistry (for VEGF, Flt-1, Flk-1, CD14, CD34, and CD68) the development of placental vasculogenesis during very early stages of pregnancy (days 22-48 p.c.) was studied. We found that VEGF is strongly expressed in villous cytotrophoblast cells and subsequently in Hofbauer cells while its receptors Flt-1 and Flk-1 are found on vasculogenic and angiogenic precursor cells. The developmental expression and secretion of VEGF suggests its involvement in recruitment, maintenance and formation of first angiogenic cells and vessels. Interactions between VEGF and Flk-1 and Flt-1 may regulate placental vasculogenesis and angiogenesis in a paracrine and autocrine manner. The sequential expression of growth factors in different cell types may point to the fact that placental vasculogenesis and angiogenesis are clearly distinct events.

Pattern of expression of cyclin D1/CDK4 complex in human placenta during gestation

Progression through the cell cycle in eukaryotic cells is controlled by a family of protein kinases, termed cyclin-dependent kinases (CDKs), and their specific partners, the cyclins. In particular, the control of mammalian cell proliferation occurs largely during the G1 phase of the cell cycle. Five mammalian G1 cyclins have been enumerated to date: cyclins D1, D2, and D3 (D-type cyclins), and cyclins E and E2. By the use of immunohistochemistry and immunoelectron microscopy, we observed that in the first trimester of gestation of human placenta, cyclin D1 was distributed in the nuclei of the cytotrophoblast compartment together with a weak positivity of endothelial cells surrounding blood vessels. The endothelial positivity of cyclin D1 strongly increased in the third trimester of gestation. Moreover, we observed the subcellular localization of cyclin D1 that was present both in the stroma of placental villi and in the nuclei of syncytiotrophoblast cells. Therefore, we observed that CDK4 was localized in the nuclei of the cytotrophoblast compartment during the first and third trimesters and it also had a nuclear positivity in the endothelial cells of blood vessels at the end of the third trimester of gestation. In conclusion we may hypothesize that cyclin D1/CDK4 complex functions to regulate the cell cycle progression in the proliferative compartment of human placenta, the cytotrophoblast, during the first trimester through interaction with p107 and p130. Therefore, cyclin D1 and CDK4 seem to be involved in the control of placental angiogenesis during the third trimester of gestation.

Prenatal diagnosis of Pompe disease by electron microscopy

INTRODUCTION

Pompe disease is one of the lysosomal storage disorders caused by alpha-glucosidase deficiency. The disease is characterized by accumulation of glycogen in the lysosome. The accumulation has unique ultrastructural features, which enable a prenatal diagnosis possible by electron microscopy.

MATERIALS AND METHODS

A prenatal diagnosis of Pompe disease by electron microscopic study of chorionic villus biopsies is described in a fetus of a mother whose previous child had died of the disease.

RESULTS

Electron microscopy revealed fibrocytes with typical vacuoles filled with glycogen. A prenatal diagnosis of Pompe disease was made and subsequently confirmed by the autopsy study of the abortus.

CONCLUSION

We report the usefulness of electron microscopy for prenatal diagnosis in the first trimester of Pompe disease.

[Ultrastructural examination of the placenta in pregnancy complicated by diabetes mellitus]

BACKGROUND

Causes of fetal hypoxia in diabetic pregnancy are still unknown. Investigation of placental vascular network seems of great importance in this research area. Abnormalities in the structure of capillaries in the vasculo-epithelial membranes and role of perivascular space may be an essential factor in explanation for fetal hypoxia in diabetic pregnant women. The aim of the study was to evaluate the relationship between the vascular surface of the terminal villi to its total surface, evaluation of the endothelial structure, perivascular space and basal membrane of the trophoblast as well as analysis of the studied parameters in relation to the classes of diabetes and metabolic control.

MATERIAL AND METHODS

The study was performed on 32 placentas from women with PGDM and GDM. There were 8 pregnant women in class G1 and G2, 15 in class B, C, D, 9 in class R/F and 8 in control group. The mean diurnal glycemia in the analysed groups ranged between 90 + 22 mg/dl and 100 + 55 mg/dl (in control group 80 + 12 mg/dl). HbA1c concentrations were between 6.7 + 0.9% and 7.6 + 1.0% (in control group 6.0 + 0.5%). Placentas were examined using light microscopy and electron microscopy Opton-Zeiss EM-900.

RESULTS

Decrease in the vascular surface of terminal villi was found in PGDM with fetal hypotrophy. In this cases we observed separation of basal membranes in basal capillaries and distention and proliferation of endothelial cells, disarrangements of perivascular space,. In placentas of women with hyperglycemia and fetal macrosomia there was a significant thickening of basal membranes of the trophoblast, and structural abnormalities in perivascular space with proliferation of collagen in terminal villi. Intensity of these changes was related to the degree of hyperglycemia and affected fetal and neonatal wellbeing. Examination of the placentas in women with PGDM with normal sugar levels before and during pregnancy revealed no or very limited pathological changes on light and electron microscopy. No significant relationships were shown between vascular surface in terminal villi and selected biochemical parameters and neonatal condition in diabetic pregnant women with fetal eutrophy

CONCLUSIONS

Pathologic changes in the placentas of diabetic women (significant thickening of basal membranes of trophoblast separation of basal membranes in basal capillaries, distention and proliferation of endothelial cells, disarrangements of perivascular space and decrease of vascular surface of terminal villi are significant factors contributing to fetal anoxia in pregnancy complicated by diabetes mellitus.

Ultrastructural study on human placenta from intrauterine growth retardation cases

A morphological study was performed on 27 human placentas from normal gestations (Group 1) and compared with those from eight cases of intrauterine growth restriction (IUGR) (Group 2). Semithin section light microscopy, transmission, and scanning electron microscopy were carried out on trophoblastic terminal villi, carefully identified under the stereomicroscope. In growth retardation cases, villi appear longer, thinner, and less vascularized, compared to the normal condition. Fibrinoid, an extracellular material of hematic origin, frequently fills villar stroma. The density of apical microvilli appears considerably reduced and occasional microvilli-free areas are observed in growth retardation cases. Moreover, the underlying basal membrane appears significantly thicker than that of normal syncytiotrophoblast. Recently, particular attention has been paid to apoptosis as a possible cell deletion mechanism in growth restriction. In our study, a majority of typical apoptotic features appear indifferently in both IUGR and normal pregnancy. Our data hints that growth retardation might be correlated with a complex of structural changes, suggestive of maternofetal traffic downregulation, but further studies are required to understand the underlying functional mechanisms.

Post-zygotic origin of isochromosome 12p

OBJECTIVE

Advance knowledge about the mechanism of isochromosome formation.

METHODS

Echographic examination of the foetus. G- and/or T-banded chromosome and FISH analysis using chromosome 12p subtelomeric probes on short- and long-term CVS cultures, amniocytes and foetal fibroblasts. Polymorphic CA repeat analysis on DNA from the foetus and both parents.

RESULTS

Short-term CVS cultures showed a 46,XX karyotype, whilst long-term CVS cultures showed a 47,XX,+12 karyotype. FISH on amniocytes indicated 2, 3 and 4 signals. Foetal fibroblasts showed both 47,XX,+12 and 47,XX,+i(12)(p10) karyotypes. DNA analysis revealed the isochromosome to be paternal in origin, whilst the other two foetal chromosomes 12 were maternal, part iso- and part heterodisomy.

CONCLUSION

The cytogenetic and DNA constitution of the foetus indicated the isochromosome 12p to be of paternal origin, and implied post-zygotic formation of the isochromosome 12p in the Pallister-Killian syndrome.