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PubMed2001

Management of prenatally detected trisomy 8 mosaicism.

We report on ten pregnancies with trisomy 8 mosaicism. Nine cases were prenatally detected in chorionic villi (n=6), amniotic fluid (AF) cells (n=2) or fetal blood (FB) lymphocytes (n=1). Follow-up laboratory investigations showed confined placental mosaicism (CPM) or pseudomosaicism in eight cases. In one case with ultrasound abnormalities, trisomy 8 mosaicism was detected in FB cells although cultured AF cells showed normal cells only. Another case of mosaic trisomy 8 was prenatally missed; cytogenetic analysis of short-term cultured villi revealed a normal male karyotype, while postnatally, trisomy 8 mosaicism was detected in peripheral blood lymphocytes and skin fibroblasts of the affected child. These findings indicate the difficulties in the prenatal diagnosis of trisomy 8 mosaicism. When found in chorionic villi, it mostly represented CPM, while in a case of true fetal trisomy 8 mosaicism, the cytotrophoblast cells showed a normal karyotype. So, the cytotrophoblast compartment of chorionic villi is a poor indicator of the presence or absence of fetal trisomy 8 mosaicism. Follow-up investigations including amniocentesis and especially fetal blood sampling are required to come to a definite prenatal diagnosis of trisomy 8 mosaicism.

Amniocentesis↗
PubMed1995

XIST expression is repressed when X inactivation is reversed in human placental cells: a model for study of XIST regulation.

Considerable evidence suggests that the X inactive transcript gene, XIST/Xist, has a role in the initial steps of X chromosome inactivation in the female mammalian embryo. It is transcribed exclusively from inactive X chromosomes, and its noncoding transcript seems to be essential for cis inactivation. Unexpected for a developmental gene, XIST continues to be expressed in adult somatic cells. To determine the effect of reversal of inactivation on the expression of XIST, we studied human X chromosomes that had been induced to reverse X inactivation by hybridization of chorionic villi cells from term placentas with mouse A9 cells. In nine hybrids with a reactivated X chromosome, XIST was either not expressed or expressed much less than the locus on the inactive X chromosome in the chorionic villi cells from which they were derived. The repressibility of XIST by reversal of inactivation in these placental cells mirrors events that occur during the ontogeny of oocytes and indicates that the locus is subject to regulation in somatic cells long after inactivation is established in the embryo. The small residual XIST activity from these active chromosomes suggests that low levels of XIST expression do not interfere with chromosome activity and raises the possibility that the induction of cis inactivation requires a certain level of XIST transcription. The chorionic villi hybrids provide an experimental system to study the developmental regulation of XIST.

Base Sequence↗
PubMed1994

The CpG island of the FMR-1 gene is methylated differently among embryonic tissues: implication for prenatal diagnosis.

We studied the methylation status of the CpG island of the FMR-1 (fragile X syndrome) gene to recognize the possibility of its prenatal diagnosis with early pregnant subjects. Southern hybridization using EcoRI/BssHII restriction enzymes double digestion was performed in the brain and chorionic villi of 8th week embryos, and the placenta and cord blood of newborns. No methylation of the FMR-1 gene occurred in both of the tissues examined in males, while 50% of the cells in females were methylated in both the brain and the cord blood, indicating that methylation occurs with inactivation of the X-chromosome in accordance with the literature. However, there was no methylation in either the chorionic villi or placenta in female as well as in males. Some extra-embryonic tissues such as the chorionic villi and the placenta escape X-chromosome FMR-1 gene inactivation and it can be the exception in the lyonization. To assess the methylation status in prenatal diagnosis, precautions are needed and they are not suitable for prenatal diagnosis.

Blotting, Southern↗
PubMed1991

First-trimester diagnosis of an unusual case of alpha-mannosidosis.

Chorionic villi obtained in the first trimester from a pregnancy at risk for alpha-mannosidosis were shown to have reduced alpha-mannosidase (EC 3.2.1.24) activity. The pregnancy was terminated and subsequent enzyme studies of the fetal tissues were consistent with the diagnosis of alpha-mannosidosis. Like the enzyme in the child's fibroblast, alpha-mannosidase of the chorionic villi from a pregnancy at risk for alpha-mannosidosis was activated by high substrate concentration and by Zn2+, and displayed a Km value two-fold higher than normal. Our results confirm that chorionic villi can be used for early prenatal diagnosis of alpha-mannosidosis.

Brain↗
PubMed2005

46,XY,18q+/46,XY,18q- mosaicism in a fragile X prenatal diagnosis.

OBJECTIVES: We describe a fetus with confined placental mosaicism for 46,XY,dup(18)(q21q23)/46,XY, del(18)(q21) in which finally the 18q- cell line formed the embryo. This prenatal diagnosis was performed on a pregnant woman carrying a premutation in the FMR1 gene. The purpose of the current study was to characterise the final fetus genotype and to discuss how this chromosomal abnormality was originated. METHODS: Conventional cytogenetic analyses were performed from chorionic villi, amniocytes, and fetal blood samples in order to establish the fetal chromosome constitution. Molecular studies with microsatellite markers and CGH were carried out to this end. PCR and Southern blot were used to analyse the CGG-repeat region of the FMR1 gene. RESULTS: An initial chorionic villi sample analysis showed a normal allele for the fragile X syndrome, but an abnormal 46,XY,dup(18)(q21q23) karyotype. Amniocentesis was subsequently performed, and a different 46,XY,del(18)(q21) cell line was detected. Re-examination of original chorionic villi sample evidenced a mosaicism for 46,XY,dup(18)(q21q23)/46,XY,del(18)(q21). Molecular findings allowed us to determine that the deletion expands at least 20 Mb and that it is paternally inherited. CONCLUSION: Two different cell lines with structural abnormalities on chromosome 18 were formed as a consequence of an unequal sister chromatid exchange during the first post-zygotic division. This case reinforces the necessity of performing a karyotype in all prenatal diagnosis even when the indication is for a monogenic disease.

Adult↗
PubMed1990

Chromosomal mosaicism in chorionic villus sampling.

The observation of multiple, chromosomally distinct cell lines in chorionic villus samples is not an unusual finding and occurs in 1 per 100 samples. This frequency is ten times greater than the level of mosaicism observed in newborn surveys and, thus, must reflect phenomenon other than true fetal mosaicism. Indeed, only 23% of mosaicism detected at CVS is confirmed in the fetus (2.3 per 1,000 CVS), which is much closer to the newborn rate (1 per 1,000). This indicates that most mosaicism encountered in CVS is unrelated to the fetal karyotype and as such is an inaccurate prediction of the fetal genotype, the purpose of prenatal diagnosis. Most of the mosaicism detected in CVS is due to confined placental mosaicism. Either as a result of error-prone cell division generating an excess of abnormal cells in extraembryonic tissues or reduced selection against aneuploid cells in these tissues allowing their persistence, chorionic villi and placenta appear to show much higher levels of mosaicism than seen in fetuses. This explains the more frequent finding of multiple cell lines in CVS than in amniocentesis or liveborn individuals. The discrepancy between levels of mosaicism present in chorionic villi and fetal tissues means that most instances of mosaicism detected in CVS are not associated with a fetal abnormality and should be evaluated by further prenatal testing, i.e., amniocentesis or fetal blood sampling. Because of the frequency of chromosomal mosaicism in CVS and its attendant need for further testing, a discussion of mosaicism should be included in counseling prior to CVS. The higher frequency of discrepant results in direct CVS preparation emphasizes the prudence of delaying decision making until the results of the CVS culture have been obtained. Although the observation of mosaicism clearly complicates genetic counseling and decision making, it does not appear to be associated with an adverse fetal outcome. Whereas most of the mosaicism observed in CVS is the result of confined placental mosaicism, other types of discrepancies also occur. Maternal cell contamination occurs in about 1% of cases, but is easily evaluated by examining the direct preparation and analyzing chromosome polymorphism. The incidence of pseudomosaicism in CVS cultures is unclear but probably low. Interestingly, CVS analysis has suggested that twinning may be a more common phenomenon at conception than reported at birth and that some discrepancies may reflect the nonviability of twins with abnormal karyotypes. Chorionic villi sampling remains a viable alternative to amniocentesis for early prenatal diagnosis. An understanding of the origins of mosaicism in CVS is necessary for

Chimera↗
PubMed1992

Tumor necrosis factor-alpha inhibits human chorionic gonadotropin secretion.

The placenta is a major source of tumor necrosis factor-alpha (TNF alpha) and is rich in TNF alpha receptors. TNF alpha inhibited hCG secretion by normal chorionic villi at 6 weeks gestation, but chorionic villi contain the heterogenous cell population. To investigate the direct effects of TNF alpha on trophoblasts, the NUC1 choriocarcinoma cell line was used as an in vitro placental cell model. TNF alpha also inhibited hCG secretion by NUC1 cells at concentrations from 1-100 U/mL. TNF alpha at concentrations of 1, 10, and 100 U/mL significantly decreased hCG secretion for 24 h to 88%, 81%, and 71% of the control level, respectively. The expression of hCG beta mRNA was also decreased to 23% of the control level after 24 h of TNF alpha treatment (100 U/mL). Inhibition occurred after 12 h of TNF alpha treatment (100 U/mL). Two measurements, trypan blue dye exclusion and 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide reduction, revealed that these inhibitory effects were not due to the cytotoxic activity of TNF alpha on NUC1. In conclusion, TNF alpha reduces hCG secretion in vitro.

Blotting, Northern↗
PubMed1996

Partial trisomy/monosomy 6q in fetal cells and CVS long-term culture not present in CVS short-term culture.

A cytogenetic discrepancy in chorionic villi with implications for prenatal diagnosis is described. Chromosome analysis revealed a normal karyotype in banded metaphases from short-term culture and a chromosome count of 46 in cells of the long-term culture. After the birth of a malformed infant, a structurally aberrant chromosome 6 was found in lymphocytes and skin fibroblasts. Re-analysis of chorionic villi confirmed the result from short-term culture but disclosed the presence of the structural aberration in cells of the long-term culture. This type of inconsistency is reported for the first time and stresses the importance of a numerical and structural analysis of both short-term and long-term culture. The application of three techniques, chromosome banding, comparative genomic hybridization (CGH), and fluorescence in situ hybridization (FISH) analysis, was essential to prove that the derivative chromosome carried a combined partial trisomy/monosomy for 6q. The findings are discussed with respect to the origin of the structural aberration and to the consequences for prenatal diagnosis on chorionic villi and genetic counselling.

Adult↗
PubMed1984

First-trimester prenatal diagnosis of Tay-Sachs disease.

The prenatal diagnosis of Tay-Sachs disease was made in two at-risk fetuses by the analysis of chorionic villi obtained at 9 and 11 menstrual weeks, respectively. The diagnoses were based on the absence of beta-hexosaminidase A activity as determined by: (1) specific enzyme assays, (2) anion-exchange chromatography, and (3) cellulose acetate gel electrophoresis. The enzymatic diagnoses were confirmed on fetal tissue as well as by ultrastructural demonstration of the first-trimester fetal neuropathology. Optimal assay conditions for beta-hexosaminidase A in chorionic villi were established for the prenatal diagnosis of Tay-Sachs disease. Importantly, it was noted that a small amount of decidua or maternal blood could lead to misdiagnosis. Thus, extreme care must be taken in the preparation of chorionic villi for Tay-Sachs as well as other prenatal metabolic diagnoses.

Brain↗
PubMed2005

Forensic applications of laser capture microdissection: use in DNA-based parentage testing and platform validation.

AIM: To report on the successful use of Laser Capture Microdissection (LCM) as a tool for isolation of human chorionic villi from admixed maternal tissue. Subsequent DNA isolation for forensic short tandem repeat (STR) analysis for parentage testing was performed in two cases of alleged sexual assault of female victims. We also performed validation of the LCM instrument platform, using archival formalin-fixed human fetal products of conception (POC), for which microdissection was utilized to separate maternal (decidua) and fetal (chorionic villus) components. METHODS: To isolate DNA from placental chorionic villi admixed with maternal decidua recovered after spontaneous or therapeutic abortion, LCM was used to separate fetal from maternal cells. In contrast to the relatively crude conventional microdissection performed using a narrow pipette, needle, or scalpel blade, LCM allows cell- or tissue-specific isolation of placental chorionic villi from archival paraffin-embedded tissue sections, leaving the maternal tissue intact. RESULTS: After polymerase chain reaction (PCR) amplification of villi after LCM of 9-15 STR loci, the quantity and quality of DNA yielded from fetal cells isolated by LCM was sufficient for PCR analysis and successful forensic parentage testing. The validation data obtained on two sets of formalin-fixed archival POC tissues from anonymous donors demonstrated the encouraging reproducibility of these protocols and procedures. CONCLUSION: We demonstrated the reliability and utility of LCM for forensic applications when high specificity of a particular analyzed cell population or tissue is required. Care must be taken during routine pathology procedures to avoid contamination of tissues with admixture of extraneous DNA.

Adolescent↗
PubMed1998

DNA methylation of the extraembryonic tissues: an in situ study on human metaphase chromosomes.

DNA methylation level and pattern of human metaphase chromosomes from extraembryonic tissues (chorionic villi and placental fibroblasts) were analysed in situ. The DNA methylation global level of these tissues was studied by comparing them with the one observed in fetal fibroblasts and adult lymphocytes. In order to assess the tissue specificity and significance of the observed differences, chromosomal preparations were then treated in parallel. They were first stained with distamycin A/DAPI and pictured, then treated with immunofluorescent staining using monoclonal antibodies raised against 5-methylcytosine. Compared with metaphases from lymphocytes or placental and fetal fibroblasts, distamycin-A/DAPI stained metaphases and constitutive heterochromatic regions with very similar intensities. In contrast, in chorionic villi, the immunofluorescent intensities revealing the presence of 5-methylcytosine was much duller than in the other tissues. In addition, in both chorionic villi and placental fibroblasts, large differences were observed between various chromosome structures within individual metaphases. In particular, the secondary constriction of chromosome 9, the distal segment of chromosome Y and the short arms of acrocentric chromosomes exhibited a much lower staining than the one observed for the secondary constrictions of chromosome 1 and 16 of the same metaphases. Because all these structures are known to be deeply methylated in other somatic tissues, this suggests that in extraembryonic tissues DNA methylation level remained hypomethylated and the pattern is under precise control.

Adult↗
PubMedDate not supplied

Mitosis of the Hofbauer cell: possible implications for a fetal macrophage.

Human chorionic villi from placentae collected during the first half of pregnancy were examined by light microscopy and transmission electron microscopy. In serial semithin sections mitoses of Hofbauer cells, as well as those of other cellular components of the villous stroma, were generally easily identified. In some cases, when the Hofbauer cells showed very few vacuoles, thin sections were helpful in differentiating this cell type from the fixed stromal cells. Hofbauer cells in mitotic division were not uncommon, but were irregularly distributed. Mitosis of the Hofbauer cells could be a mechanism involved in maintaining the permanent presence in the chorionic villi of cell subpopulations with different origins and functions. Another explanation for the mitotic division of these cells could be that they are a self-renewing population independent of fetal monocytes which appear later in gestation in chorionic villi. In addition, mitosis of the Hofbauer cells could allow a rapid increase in their numbers when required by the local microenvironment.

Chorionic Villi↗
PubMed1987

Experience with first trimester prenatal diagnosis of Menkes disease.

We have performed 28 first trimester diagnoses for Menkes disease in 27 high risk pregnancies by direct copper measurement on chorionic villi (c.v.) Two male fetuses were found to be affected because of significantly increased copper content. In one male fetus a slightly increased copper content was observed indicating an exogenous copper contamination of the sample. This view was supported by normal results observed after abortion. Three out of 15 diagnostic c.v. samples with a female karyotype showed increased copper levels. In two of these cases, part of the copper content might have been released from the cannulae used for these particular biopsies. Histochemical visualization of copper accumulation in fixed chorionic villi of two affected fetuses and one female fetus was observed. [64Cu]-uptake studies have been performed on 11 diagnostic and 10 control c.v. samples. As the control samples in some cases were found to incorporate more [64Cu] than the corresponding diagnostic sample, this method cannot at present be used for diagnosis. Compiled results on newborn females gave evidence that two carriers expressed the paternal X-chromosome, and two carriers expressed the maternal X-chromosome in in chorionic villi.

Adult↗
PubMed1990

[A comparative study of the karyotypes of fetuses of spontaneous early abortions obtained by direct method and by long-term culture].

The direct method of chromosomal preparations on chorionic villi biopsies has been applied to the cytogenetic study of 34 early spontaneous abortion products. These results were compared with those obtained through long term cultures performed simultaneously from the same samples. The success rate obtained through the direct method (86.2%) is superior to that of the long term culture (76.4%). However, the combined use of both techniques further improves the success rate (94.1%) and the reliability of the results. Among the 32 informative cases, 15 chromosomal aberrations (46.8%) have been detected. These data demonstrate the value of the direct method of karyotyping chorionic villi from spontaneous abortion products. However, considering the specific advantages of either method respectively, the authors recommend that both be used simultaneously for optimal diagnostic efficiency.

Abortion, Spontaneous↗
PubMed2004

Growth and function of the normal human placenta.

The placenta is the highly specialised organ of pregnancy that supports the normal growth and development of the fetus. Growth and function of the placenta are precisely regulated and coordinated to ensure the exchange of nutrients and waste products between the maternal and fetal circulatory systems operates at maximal efficiency. The main functional units of the placenta are the chorionic villi within which fetal blood is separated by only three or four cell layers (placental membrane) from maternal blood in the surrounding intervillous space. After implantation, trophoblast cells proliferate and differentiate along two pathways described as villous and extravillous. Non-migratory, villous cytotrophoblast cells fuse to form the multinucleated syncytiotrophoblast, which forms the outer epithelial layer of the chorionic villi. It is at the terminal branches of the chorionic villi that the majority of fetal/maternal exchange occurs. Extravillous trophoblast cells migrate into the decidua and remodel uterine arteries. This facilitates blood flow to the placenta via dilated, compliant vessels, unresponsive to maternal vasomotor control. The placenta acts to provide oxygen and nutrients to the fetus, whilst removing carbon dioxide and other waste products. It metabolises a number of substances and can release metabolic products into maternal and/or fetal circulations. The placenta can help to protect the fetus against certain xenobiotic molecules, infections and maternal diseases. In addition, it releases hormones into both the maternal and fetal circulations to affect pregnancy, metabolism, fetal growth, parturition and other functions. Many placental functional changes occur that accommodate the increasing metabolic demands of the developing fetus throughout gestation.

Carbohydrates↗
PubMed1987

Implications of the placental structure compatibility for interspecies embryo transfer.

Comparative histological features of the chorionic villi in placental cotyledons of the common eland (Taurotragus oryx ) and bongo (Boocercus euryceros ) antelopes and okapi (Okapia johnstoni ) and giraffe (Giraffa camelopardalis ) were examined. The chorionic villi in both antelope species showed only moderate branching and/or surface corrugation and their cross-sections were polygonal to oval. The close similarity in the structure of cotyledons has been apparently a contributing factor for success in mutual interspecies embryo transfer. The chorionic villi in okapi and giraffe had very different structures. In okapi the villi on cross-section were round and filled with thin connective tissue. They showed minimal branching and surface corrugation. In giraffe the villi showed extensive surface corrugation, had multiple fine branches, and were filled with a more dense connective tissue. Prospect for materno-fetal compatibility in mutual embryo transfer between these species is guarded.

Journal Article↗
PubMed1996

First trimester prenatal diagnosis by transcervical chorionic villus sampling using curved biopsy forceps: lessons of the first 30 continuing pregnancies.

Transcervical chorionic villus sampling was performed on 30 pregnancies who were at risk for chromosomal abnormalities between 9 and 12 weeks of gestation to determine whether the developing fetus had a chromosomal disorder. Curved biopsy forceps were passed transcervically into the chorion frondosum under continuous real-time ultrasound guidance, and chorionic villi were biopsied. Chorion yield was assessed semiquantitatively. An adequate villus sample was obtained in all cases, giving a success rate of 100 per cent. The average weight of the villi was 18.8 mg with a lower limit of 10 mg which proved sufficient for diagnostic purposes. The villi were processed for chromosomal analyses by cultured preparations. A diagnostic result was achieved in 28 of cases (93.3%) within 2 weeks. No major maternal complications were encountered. The fetal loss rate was 3.3 per cent. No fetal anomalies were found in the study group. It is concluded that transcervical chorionic villus sampling appears to be a relatively safe and reliable procedure, but the risk of miscarriage can only be accurately assessed after further investigation. In contrast to amniocentesis, the procedure is performed early in pregnancy and results of the genetic test are available during the first trimester. We believe that transcervical chorionic villus sampling offers an alternative to amniocentesis in the detection of genetic disorders.

Abortion, Spontaneous↗