Vasculogenesis in complete and partial hydatidiform mole pregnancies studied with CD34 immunohistochemistry

B.A.M. Lisman1,2,3, K. Boer2, O.P. Bleker2, M. van Wely2 and N. Exalto1,2

1 Department of Obstetrics and Gynaecology, Spaarne Ziekenhuis Haarlem, PO Box 1644, 2003 BR Haarlem and 2 Department of Obstetrics and Gynaecology, Academic Medical Center, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, The Netherlands

3 To whom correspondence should be addressed. Email: b.a.lisman{at}amc.uva.nl


    Abstract
 Top
 Abstract
 Introduction
 Material and methods
 Results
 Discussion
 References
 
BACKGROUND: Defective chorionic villous vascularization is present in pregnancies complicated by absent or abnormal embryonic development. The aim of this study was to investigate the embryonic and/or maternal genomic influence on vasculogenesis in diploid complete hydatidiform mole (CHM) and in triploid partial hydatidiform mole (PHM) in comparison with normal development. METHODS: Mean villous stromal area and functional vascular area, vessels with a lumen and haemangiogenetic cords, peripherally or centrally located were measured and counted in chorionic villi of 12 CHM, 12 normal pregnancies (termination of pregnancy, TOP) and 15 PHM of which nine were without an embryo (PHM–E) and six were with an embryo (PHM + E), using quantitative CD34 immunohistochemistry. RESULTS: TOP showed significantly more vessels per chorionic villus, centrally and peripherally located (median, range), than CHM, PHM–E and PHM + E (4.0, 0–9 versus 0.0, 0–11, 0.0, 0–18 and 1.0, 0–21). CHM showed significantly more centrally located cords than PHM–E, PHM + E and TOP (1.5, 0–22 versus 1.0, 0–15, 0.5, 0–8 and 1.0, 0–2). CONCLUSIONS: Initiation of chorionic villous vasculogenesis is independent of the maternal genome (CHM). The development of an embryo, however, is obligatory for the modulation of normal vascularization resulting in a well developed vasculosyncytial membrane.

Key words: CD34/chorionic villous/complete hydatidiform mole/partial hydatidiform mole/vasculogenesis/triploidy


    Introduction
 Top
 Abstract
 Introduction
 Material and methods
 Results
 Discussion
 References
 
Hydatidiform mole is a phenotype with two different entities having different histopathological and cytogenetic criteria: the complete hydatidiform mole (CHM) and the partial hydatidiform mole (PHM).

CHM arises from the fertilization of an empty oocyte (the maternal pronucleus is lacking or inactivated) by two haploid sperm (heterozygous) or by one haploid sperm followed by duplication of its chromosomes (homozygous). Genetic studies have demonstrated that the majority of CHM are androgenetic and diploid with a predominantly 46 XX karyotype. The 46 XY karyotype is less common and 46 YY has never been found (Kajii and Ohama, 1977Go; Jacobs et al., 1980Go; Lawler et al., 1991Go). CHM is characterized by generalized swelling of the villi (stromal oedema with formation of cisterna), diffuse trophoblastic hyperplasia and absence of embryonal tissues (Szulman and Surti, 1978Go).

Although the villous stroma of CHM is avascular in the classical descriptions, a few studies have demonstrated blood vessels in villi of CHM without embryonal blood cells. In the majority of CHM, some vasculogenesis is present, mainly in the villi with little or no oedema (Pardinas et al., 1996Go; Qiao et al., 1997Go; van de Kaa et al., 1997Go).

It has been suggested that the absence of a maternal contribution to the nuclear genome in CHM (paternal origin) will result in the inability to form an embryo (Szulman and Surti, 1978Go). As in recent studies, however, some early embryonic development has been found (nucleated blood cells, amniotic tissue and yolk sac), it is presumed that the embryonic development will stop very early in these pregnancies (Fisher et al., 1997Go; Paradinas et al., 1997Go; van de Kaa et al., 1997Go; Weaver et al., 2000Go).

PHM is characterized by focal swelling of the villous tissue, focal trophoblastic hyperplasia and often the presence of an embryo or fetal tissue, with >90% of them being triploid (Szulman et al., 1981Go). Triploidy may either arise through fertilization of a haploid oocyte by two spermatozoa (diandric) or through the fertilization of a diploid oocyte by one sperm (digynic). PHM is the phenotype of diandric triploidy (Jacobs et al., 1982Go; Zaragoza et al., 2000Go). Digynic triploid pregnancies are not associated with PHM but show severely restricted embryonic growth with relative macrocephaly and a very small placenta.

The monoclonal antibody against CD34 antigen in human endothelial cell membranes and haemopoietic progenitor cells proved to be a useful marker of villous vascular endothelial cells in normal first trimester pregnancies (te Velde et al., 1997Go) and complicated pregnancies in the first and second trimester (Qiao et al., 1997Go; Lisman et al., 1998Go; Lisman and Exalto, 1999Go).

In a recent study, using CD34 immunohistochemistry, we have demonstrated an abnormal development of the vasculosyncytial membrane in pregnancies complicated by embryonic death and even more in anembryonic pregnancies. It was concluded that vasculogenesis is a basic feature in all types of pregnancy and is subsequently modulated directly or indirectly by embryonic signalling (Lisman et al., 2004Go).

The aim of the present study is to investigate the embryonic and/or maternal genomic influence on vasculogenesis in CHM and in PHM, with chromosomes exclusively and predominantly, respectively, of paternal origin, in comparison with normal development.


    Material and methods
 Top
 Abstract
 Introduction
 Material and methods
 Results
 Discussion
 References
 
Case selection
Records of patients with CHM, PHM or termination of pregnancy (TOP) at the Departments of Gynaecology and Obstetrics at the Spaarne Hospital and at the Academic Medical Center, University of Amsterdam during recent years were retrieved. CHM were proved to be all diploids by DNA analysis. All cases of PHM were proved to be triploid either by DNA analysis or by karyotype. Two groups of 12 pregnancies each (CHM and TOP) and one group of 15 pregnancies (PHM) subdivided into one group of nine PHM without an embryo and one group of six PHM with an embryo or fetus, were recruited by selecting consecutive cases fulfilling the following inclusion criteria: group I, CHM (not containing embryonic signs such as a stunted embryo, yolk sac or amnion on ultrasound); group II, subdivided into group IIA, PHM without an embryo (PHM–E; not containing embryonic signs such as a stunted embryo, yolk sac or amnion on ultrasound) and group IIB, PHM with an embryo or fetus [PHM + E; crown–rump length (CRL) or DBP available with or without positive heart action]; group III, TOP (CRL available, positive heart action). The Dutch Central Molar Registration, University Medical Center St Radboud, Nijmegen revised all group I, IIA and IIB slides. As the selection was based on ultrasound criteria, we preferred the term PHM without an embryo over early embryonic demise in PHM pregnancy although the latter seems to be more appropriate from a morphogenetic point of view.

Gestational age (GA) was calculated based on the CRL measured in a viable state of the embryo (TOP and PHM + E) or based on the last menstrual period (CHM and PHM–E). In three cases of PHM + E, the embryo was in a viable condition; in the other three cases, the embryo was in the post-mortem state before dilatation and curettage (D&C).

In all cases, routinely phosphate-buffered formalin-fixed paraffin blocks were retrieved and stained with haematoxylin and eosin (H&E) and anti-CD34 antibody.

According to Dutch law, no approval of the Institutional Review Board was obligatory for the performance of these histopathological measurements. However, this study was performed with the approval of the Science Committee of the Spaarne Hospital.

Immunohistochemistry
Placental tissue sections (4 µm thick) were cut and mounted on 3-aminopropyl-triethoxy-silane-coated slides. Incubation with monoclonal mouse-antiCD34 antibody (Biiogenex, San Ramon, CA) was performed at room temperature for 1 h, after blocking endogenous peroxidase activity. Detection of the primary antibody was performed using biotinylated rabbit anti-mouse antibody (DAKO A/S, Copenhagen, Denmark) and streptavidin–biotin–horseradish peroxidase complex (sABC/HRP, DAKO A/S, Denmark). The peroxidase reaction was visualized using diaminobenzidine/H2O2 [0.05% (w/v)/0.03% (v/v)].

Analysis of vasculogenesis
Slides of placenta tissue of CHM and PHM were examined at a magnification of x40 (field diameter 4500 µm) and placenta tissue of TOP was examined at a magnification of x100 (field diameter 1800 µm) by one trained observer, blind to the group and duration of the pregnancy. For each case, 15 randomly selected mesenchymal or immature intermediate villi (without stromal connective tissue fibres to rule out stem villi) were evaluated. According to a previously performed pilot study to obtain stable running means for villous stromal area, functional vascular area and vascular elements, 15 villi appeared to be sufficient for a stable outcome of measurements. The outcome of measurement for the different variables, studying 15 villi per pregnancy specimen, yielded an intra-observer variability of <15% (unpublished data). In 15 villi of each pregnancy, the total amount of vascular elements was counted.

The process of maturation was depicted by counting cords, defined as clusters of CD34-positive haemangioblastic cells without lumen formation, as well as vessels, defined as clusters of CD34-positive cells with a clear cut lumen. The process of margination was illustrated by describing whether these cords and vessels were located peripherally or centrally. Peripherally was defined as situated in contact with the trophoblastic surface of the villus, contributing to the vasculosyncytial membrane as such. Centrally was defined as without any connection to the trophoblast (Figure 1a).



View larger version (130K):
[in this window]
[in a new window]
 
Figure 1. Chorionic villous vascularization of normal first trimester pregnancy (a) and CHM (b). Luminized vessels (V) and haemangiogenetic cords (C), located centrally (c) and peripherally (p).

 
Morphometrical analysis
Morphometrical measurements were performed using the QPRODIT interactive video-overlay system (Leica, Cambridge, UK). The system comprises an IBM-compatible microcomputer with a video overlay board, a computer mouse and a charge-coupled device colour camera mounted on a standard light microscope. After a rough examination for fields with a sufficient number of chorionic villi, 15 villi were randomly selected by the computer using an on-screen grid. Only villi which could be visualized completely, which means including the syncytiotrophoblast, were measured. Contours of the stroma of the previously mentioned 15 villi and all the included vessels were traced manually on the computer monitor with a mouse-controlled cursor using an on-screen magnification of x100.

The following features were calculated: area of the villous stroma without the trophoblastic layer; functional vascular area; the percentage of villous stroma occupied by vessels; all the vessels and cords; and the amount of central and peripheral cords and vessels. The vascular density of vascularized villi was calculated separately after excluding avascular villi and was defined as the mean number of vessels per vascularized villus.

Statistical analysis
Differences between groups in patient characteristics, number of central and peripheral cords and vessels, the area of villous stroma including vessels and the vascular area were tested for significance, using analysis of variance or median tests as appropriate. Significant differences were studied further by post hoc analyses. Data were analysed using SPSS 11.5.1 (SPSS Inc., Chicago, IL).


    Results
 Top
 Abstract
 Introduction
 Material and methods
 Results
 Discussion
 References
 
Patient's characteristics
A total of 39 pregnancies divided into four groups were studied. Group I consisted of 12 CHMs, group IIA consisted of nine PHM–E, group IIB consisted of six PHM + E and group III consisted of 12 normal pregnancies (TOP). Patient characteristics are presented in Table I.


View this table:
[in this window]
[in a new window]
 
Table I. Mean (SEM) patients characteristics at the time of termination of pregnancy

 
The mean GA of PHM–E and PHM + E was higher (93.8 and 103 days, respectively) than that of CHM and TOP (75.1 and 59.7 days, respectively); these differences did not reach statistical significance.

Morphometric measurements
The median (range) number of various vascular elements in 15 chorionic villi for the different groups is described in Table II.


View this table:
[in this window]
[in a new window]
 
Table II. The median (range) number of vascular elements (in 15 chorionic villi) of CHM, PHM without embryo, PHM with embryo or fetus and normal pregnancies (TOP)

 
The total number of vascular elements (vessels and cords) in CHM and PHM–E was lower compared with PHM + E and TOP, although the difference with TOP was not statistically significant. No (statistically significant) difference in the total number of vascular elements was found between CHM and PHM–E and between PHM + E and TOP.

CHM showed statistically significantly more cords, mainly centrally located, in comparison with PHM–E, PHM + E and TOP. This difference, although less prominent, was also seen in PHM–E in which more centrally located cords were present in comparison with PHM + E and TOP. Between PHM + E and TOP, no statistically significant difference was seen with respect to cords.

In TOP, significantly more vessels with a lumen, centrally and peripherally located, were present in comparison with CHM, PHM–E and PHM + E (Figure 2). Also PHM + E showed significantly more vessels than CHM and PHM–E, but less vessels compared with TOP (not statistically significant).



View larger version (131K):
[in this window]
[in a new window]
 
Figure 2. Chorionic villous vascularization in PHM–E (a) and PHM+ E (b). Luminized vessels (V) and haemangiogenetic cords (C), located centrally (c) and peripherally (p) in chorionic villi with trophoblast inclusions (TI).

 
Chorionic villi characteristics
The villous stromal area and functional vascular area (vessels with a lumen) are presented for CHM, PHM–E, PHM + E and TOP in Table III. The villous stromal area in CHM, PHM–E and PHM + E is significantly larger than in TOP. No statistically significant difference in villous stromal area was found between PHM–E and PHM + E.


View this table:
[in this window]
[in a new window]
 
Table III. Villous stromal area and functional vascular area (vessels with a lumen per 15 chorionic villi) in CHM, PHM without embryo, PHM with embryo or fetus and normal pregnancies (TOP), presented as mean (±SEM)

 
The functional vascular area in CHM is significantly smaller than in TOP, PHM–E and PHM + E. Only the difference between CHM and TOP reached statistical significance.

In CHM, 0.02% of the stromal area of the chorionic villi consisted of functional vascular area (vessels with a lumen), compared with 0.15% in PHM–E, 0.20% in PHM + E and 0.70% in TOP.

The prevalence of functional vascularized villi (vessels with a lumen) in the CHM group was 16%, in the PHM–E group 37%, in the PHM + E group 54% and in the TOP group 93%. The vascular density of these functional vascularized villi for the different groups was 2.6 for the CHM group, 3.1 for the PHM–E group, 5.8 for the PHM + E group and 5.6 for the TOP group.


    Discussion
 Top
 Abstract
 Introduction
 Material and methods
 Results
 Discussion
 References
 
In the CHM and PHM–E groups, we observed a low number of total vascular elements (cords and vessels) compared with the PHM + E and TOP groups. A low number of luminized vessels was seen in the CHM group and in both groups of PHM as compared with the control group (TOP). As compared with all other groups, the largest number of central cords was seen in the CHM group. There was also a statistically significant smaller functional vascular area in CHM in comparison with TOP. These differences illustrate that a normal initiation of vasculogenesis is basically present in CHM pregnancies, despite the absence of an embryo or maternal-derived chromosomes. In the group of CHM, PHM–E and PHM + E, we observed a decreased number of peripheral vessels compared with the TOP control group, illustrating a decreased maturation with abnormal development of the vasculosyncytial membrane.

The prevalence of functional vascularized villi (vessels with a lumen) in the CHM group was 16%. This is in agreement with the results of van de Kaa et al. (1997)Go, who found well formed capillaries with wide-open lumina in 17% of the cases of CHM.

Because we found even in CHM (androgenetic in origin) the presence of centrally located cords (initiation of vasculogenesis) and signs of maturation from cords to vessels, we conclude that in the absence of the maternal genome, initiation of vasculogenesis does take place. Initiation of vasculogenesis as a sign of early embryonic development is independent of maternal imprinting. This is in agreement with the results of Zaragoza et al. (1997)Go, who identified in four cases of CHM (confirmed androgenetic) extra-embryonic components including endothelial cells, concluding that the maternal genome is not required for initiation of vasculogenesis. Maternal genes are necessary for the development of the embryo itself and vasculogenesis is modulated directly or indirectly by embryonic signalling.

The phenomenon that the expression of genes in the human genome depends on their location on the maternal or paternal chromosome is known as genomic imprinting. In PHM, the maternal genome is present, but remains in the minority. Vasculogenesis is seen in PHM–E and in PHM + E, although maturation and margination resulting in a vasculosyncytial membrane is only seen in PHM + E. The presence of an embryo is therefore obligatory for the development of this membrane.

Retention time as seen in the group of PHM + E could be a point of discussion, because it can be argued that vascular changes occurred post-mortem. In previous studies, no effect of retention time was found on the outcome of vascular parameters (Meegdes et al., 1988Go; Nelen et al., 2000Go). Trophoblast hypoplasia with deficient vascularization appears to be the result of disturbed initiation of embryonic placental circulation rather than of post-mortem changes, as found in placental studies on late second or third trimester stillborn fetuses (Genest, 1992Go; Hustin et al., 1996Go).

In a recent publication, in which the development of the vasculosyncytial membrane in first trimester pregnancies complicated by embryonic death and anembryonic pregnancies was studied (Lisman et al., 2004Go), we could not find any significant influence with regard to the number of vessels with a lumen. On the contrary, villous vascularization appeared unaffected by prolonged post-mortem (pregnancies complicated by embryonic death) intrauterine retention, whereas the number of cords decreased during a prolonged retention time. Therefore, in our opinion, retention time in the three PHM + E which were in a post-mortem state before D&C did not affect vascularization.

In the group of TOP, the chorionic villi of one pregnancy showed almost no vessels peripherally as well as centrally, but did have cords both peripherally and centrally located. Although all patients underwent ultrasound to confirm embryonic viability in this group before D&C, no cytogenetic investigation was performed afterwards to rule out chromosomal abnormalities or other causes of complicated pregnancies in which abnormal development of villous vasculature can be seen (Roberts et al., 2000Go). DNA analysis or karyotyping was performed in the group of CHM and PHM; CHM were all diploids and PHM were all triploids.

The GA in the group of PHM–E and PHM+E is higher than in TOP. PHM–E and PHM+E were all diagnosed as PHM by the pathologist in combination with DNA analysis. Revision took place by the Dutch Central Molar Registration, University Medical Center St Radboud, Nijmegen. Molar transformation becomes more pronounced as pregnancy advances. If the study population consisted of triploidy of <84 days gestation, no noticeable macroscopic features of molar change would have been seen and consequently the diagnosis would not have been PHM (Jauniaux et al., 1996Go).

In normal first trimester pregnancies, an increase in GA leads to an increase in the total number of vascular elements, but the amount of cords remains stable (te Velde et al., 1997Go). This was confirmed in the group of TOP in this study. Jackson et al. (1992)Go published a quantitative description of growth and maturation of chorionic villi collected at 10–41 weeks GA. They concluded that an increase of GA leads to an increase of volume and surface area of chorionic villi and chorionic villous maturation, which involves increase of capillary volume and decrease of villous diameter leading to a well developed vasculosyncytial membrane. There was no difference in vascular density in vascularized villi for the PHM + E group and the TOP group, although the prevalence of functional vascularized villi in PHM + E was 54% and in TOP 93%. In PHM–E and PHM + E, we observed mainly cords and less vessels with a lumen in relation to TOP. Obviously, in spite of a more advanced duration of pregnancy in PHM–E and PHM + E, a normal development of the vasculosyncytial membrane is only seen in TOP. Although we acknowledge the difference in GA between the various pregnancy groups, it does not seem to have influenced the results or the conclusion as drawn from this particular study.

Conclusions from the present study
We found that the villous stromal area of CHM, PHM–E and PHM + E is significantly larger than of TOP. The functional vascular area of CHM was smaller than in PHM–E, PHM + E and TOP. There was no difference found between the functional vascular area of PHM–E, PHM + E and TOP. However, the functional vascular area needs to be related to the villous stromal area. The percentage of stromal area occupied by functional vascular area in PHM–E was 0.15%, in PHM + E 0.20% and in TOP 0.70%. Although the difference between these groups is not statistically significant, it does clearly indicate a defective maturation of cords to vessels in PHM + E and even more pronounced in PHM–E and CHM. The percentage of functional vascular area as part of the stromal area is comparable with the results we found in a recent published study on chorionic villous vascularization in first trimester pregnancies complicated by embryonic death and anembryonic pregnancies (Lisman et al., 2004Go).

In conclusion, defective chorionic villous vascularization is seen in CHM and PHM–E, and to a lesser extent in PHM + E. Chorionic villi of normal first trimester pregnancies contain more vessels than cords (maturation) and these vessels are mainly located peripherally (margination), forming a normal vasculosyncytial membrane. However, initiation of vasculogenesis is clearly present in CHM, proving that initiation of vasculogenesis does take place in the absence of the maternal genome. Nevertheless, the developing embryo modulates the process of maturation and margination resulting in the development of a normal vasculosyncytial membrane.


    References
 Top
 Abstract
 Introduction
 Material and methods
 Results
 Discussion
 References
 
Fisher RA, Paradinas FJ, Soteriou BA, Foskett M and Newlands ES (1997) Diploid hydatidiform moles with fetal red blood cells in molar villi. 2—Genetics. J Pathol 181, 189–195.[CrossRef][ISI][Medline]

Genest DR (1992) Estimating the time of death in stillborn fetuses: II. Histologic evaluation of the placenta; a study of 71 stillborns. Obstet Gynaecol 80, 585–592.[Abstract]

Hustin J, Kadri R and Jauniaux E (1996) Spontaneous and habitual abortion—a pathologist's point of view. Early Preg Biol Med 2, 85–95.

Jacobs PA, Szulman AE, Funkhouser J, Matsuura JS and Wilson CC (1982) Human triploidy: relationship between parental origin of the additional haploid complement and development of partial hydatidiform mole. Ann Hum Genet 46, 223–231.[ISI][Medline]

Jacobs PA, Wilson CM, Sprenkle JA, Rosenshein NB and Migeon BR (1980) Mechanisms of origin of complete hydatidiform moles. Nature 286, 714–715.[CrossRef][ISI][Medline]

Jackson MR, Mayhew TM and Boyd PA (1992) Quantitative description of the elaboration and maturation of villi from 10 weeks of gestation to term. Placenta 13, 357–370.[ISI][Medline]

Jauniaux E, Kadri R and Hustin J (1996) Partial mole and triploidy: screening patients with first-trimester spontaneous abortion. Obstet Gynecol 88, 616–619.[Abstract/Free Full Text]

Kajii T and Ohama K (1977) Androgenetic origine of hydatidiform mole. Nature 268, 633–634.[ISI][Medline]

Lawler SD, Fisher RA and Dent J (1991) A prospective genetic study of complete and partial hydatidiform moles. Am J Obstet Gynecol 164, 1270–1277.[ISI][Medline]

Lisman BAM, Boer K, Bleker OP, van Wely M, van Groningen K and Exalto N (2004) Abnormal development of the vasculosyncytial membrane in early pregnancy failure. Fertil Steril 82, 654–660.[CrossRef][ISI][Medline]

Lisman BAM and Exalto N (1999) Early human nutrition and chorionic villous vascularization. Middle East Fertil Soc J 4, 87–93.

Lisman BAM, Knieriem JC, van Groningen K and Exalto N (1998) Observations on chorionic villous vascularization in the late abortion period. Proceedings of the ETEP Meeting ESHRE 1998, Göteborg.

Meegdes HLM, Ingenhoes R, Peeters LLH and Exalto N (1988) Early pregnancy wastage: relationship between chorionic vascularization and embryonic development. Fertil Steril 49, 216–220.[ISI][Medline]

Nelen WLDM, Bulten J, Steegers EAP, Blom HJ, Hanselaar AGJM and Eskes TKAB (2000) Maternal homocysteine and chorionic vascularization in recurrent early pregnancy loss. Hum Reprod 15, 954–960.[Abstract/Free Full Text]

Paradinas FJ, Browne P, Fisher RA, Foskett M, Bagshawe KD and Newlands ES (1996) A clinical, histopathological and flow cytometry study of 149 complete moles, 146 partial moles and 107 non-molar hydropic abortions. Histopathology 28, 101–109.[CrossRef][ISI][Medline]

Paradinas FJ, Fisher RA, Browne P and Newlands ES (1997) Diploid hydatidiform moles with fetal red blood cells in molar villi. 1—Pathology, incidence, and prognosis. J Pathol 181, 183–188.[CrossRef][ISI][Medline]

Qiao S, Nagasaka T and Nakashima N (1997) Nummerous vessels detected by CD34 in the villous stroma of complete hydatidiform moles. Int J Gynecol Pathol 16, 233–238.[ISI][Medline]

Roberts L, Sebire D, Fowler D and Nicolaides H (2000) Histomorphological features of chorionic villi at 10-14 weeks of gestation in trisomic and chromosomally normal pregnancies. Placenta 21, 678–683.[CrossRef][ISI][Medline]

Szulman AE, Philippe E, Boue JG and Boue A (1981) Human triploidy: association with partial hydatidiform moles and nonmolar conceptuses. Hum Pathol 12, 1016–1021.[ISI][Medline]

Szulman AE and Surti U (1978) The syndromes of hydatidiform mole. I Cytogenetic and morphologic correlatios. II Morphologic evolution of the complete and partial mole. Am Obstet Gynecol 131, 665–671. 20–27.[ISI]

te Velde EA, Exalto N, Hesseling P and van der Linden HC (1997) First trimester development of human chorionic villous vascularization studied with CD34 immunohistochemistry. Hum Reprod 12, 1577–1581.[Abstract]

van de Kaa CA, Schijf CPT, de Wilde PCM, Hanselaar AGJM and Vooijs PG (1997) The role of deoxyribonucleic acid image cytometricand interphase cytogenetic analyses in the differential diagnosis, prognosis and clinical follow-up of hydatdoform moles. A report from the Central Molar Registration in The Netherlands. Am J Obstet Gynecol 177, 1219–1229.[ISI][Medline]

Weaver DT, Fisher RA, Newlands ES and Paradinas FJ (2000) Amniotic tissue in complete hydatidiform moles can be androgenetic. J Pathol 191, 67–70.[CrossRef][ISI][Medline]

Zaragoza MV, Keep D, Genest DR, Hasshold T and Redline RW (1997) Early complete hydatidiform moles contain inner cell mass derivatives. Am J Med Genet 70, 273–277.[CrossRef][ISI][Medline]

Zaragoza MV, Surti U, Redline RW, Millie E, Chakravarti A and Hassold TJ (2000) Parental origin and phenotype of triploidy in spontaneous abortions: predominance of diandry and association with the partial hydatidiform mole. Am J Hum Genet 66, 1807–1820.[CrossRef][ISI][Medline]

Submitted on September 22, 2004; resubmitted on February 7, 2005; accepted on March 23, 2005.





This Article
Abstract
Full Text (PDF )
All Versions of this Article:
20/8/2334    most recent
dei039v1
Alert me when this article is cited
Alert me if a correction is posted
Services
Email this article to a friend
Similar articles in this journal
Similar articles in PubMed
Alert me to new issues of the journal
Add to My Personal Archive
Download to citation manager
Request Permissions
Google Scholar
Articles by Lisman, B.A.M.
Articles by Exalto, N.
PubMed
PubMed Citation
Articles by Lisman, B.A.M.
Articles by Exalto, N.