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Complement regulatory proteins at the feto-maternal interface during human placental development: distribution of CD59 by comparison with membrane cofactor protein (CD46) and decay accelerating factor (CD55).

The complement (C) regulatory proteins decay-accelerating factor (DAF, CD55) and membrane cofactor protein (MCP, CD46), which control C3 convertases, together with CD59, an inhibitor of the membrane attack complex (MAC), were found to be present in the developing human placenta from at least 6 weeks of gestation until term. Immunostaining revealed differences in the distribution of these proteins on the fetally derived trophoblast epithelium, especially in early placentae which contain trophoblast populations of diverse proliferative potential and differentiation status. Expression of all three proteins occurred on the terminally differentiated syncytiotrophoblast epithelium covering chorionic villi and which is in direct contact with maternal blood. CD59 was also expressed on the underlying villous cytotrophoblast cells and on their extra-villous derivatives. These two populations showed differential expression of the C3 convertase regulators. Villous cytotrophoblast cells expressed MCP but were largely devoid of DAF. Proliferation of this population to generate extra-villous cytotrophoblast cell columns was associated with both an increase in DAF expression and a decrease in MCP expression. Throughout placental development, expression of DAF appeared to be lower than that of MCP and CD59 as assessed by solid-phase binding assays on isolated trophoblast membranes. Early placentae were also found to contain both DAF+ and DAF- chorionic villi. Conversely, expression of CD59 appeared comparatively high and transcripts for CD59 were found to be much more abundant than those for DAF in purified trophoblast cells. C regulatory proteins appear to play an important role throughout gestation in protecting the fetally derived human conceptus from maternal C. The differential expression patterns of the proteins on trophoblast may reflect differences in requirement for specific functional activities at different locations within the placenta.

Antigens, CD↗

Localization of transforming growth factor-beta at the human fetal-maternal interface: role in trophoblast growth and differentiation.

We examined the localization of transforming growth factor (TGF)-beta in first-trimester and term human decidua and chorionic villi and explored the role of this factor on the proliferation and differentiation of cultured trophoblast cells. Two antibodies, 1D11.16.8, a mouse monoclonal neutralizing antibody capable of recognizing both TGF-beta 1 and TGF-beta 2 and CL-B1/29, a rabbit polyclonal antibody capable of recognizing TGF-beta 2, were used to immunolocalize TGF-beta in fixed, paraffin-embedded, or fixed, frozen sections of placenta and decidua, providing similar results. Intense labeling was observed in the extracellular matrix (ECM) of the first-trimester decidua and cytoplasm of term decidual cells. Syncytiotrophoblast cell cytoplasm as well as the ECM in the core of the chorionic villi of both first-trimester and term placentas exhibited a moderate degree of labeling. Strong cytoplasmic labeling was observed in the cytotrophoblastic shell of the term placenta. To examine the role of TGF-beta on trophoblast proliferation and differentiation, early passage cultures of first-trimester and primary cultures of term trophoblast cells were established and characterized on the basis of numerous immunocytochemical and functional markers. These cells expressed cytokeratin, placental alkaline phosphatase, urokinase-type plasminogen activator, and pregnancy-specific beta glycoprotein, but not factor VIII or 63D3; they also produced hCG and collagenase type IV. Exposure of first-trimester trophoblast cultures to TGF-beta 1 significantly inhibited proliferation in a dose-dependent manner. An antiproliferative effect was also noted in the presence of TGF-beta 2. These effects were abrogated in the presence of the neutralizing anti-TGF-beta antibody (1D11.16.8) in a concentration-dependent manner. In a 3-day culture, exogenous TGF-beta 1 stimulated formation of multinucleated cells by the first trimester as well as term trophoblast cells. Addition of neutralizing anti-TGF-beta antibody to first-trimester trophoblast cells stimulated proliferation beyond control levels in a 24-h culture and reduced formation of multinucleated cells in a 3-day culture, indicating the presence of endogenous TGF-beta activity. These results indicate that TGF-beta produced at the human fetal-maternal interface plays a major regulatory role in the proliferation and differentiation of the trophoblast.

Alkaline Phosphatase↗

Expression of human telomerase reverse transcriptase and correlation with telomerase activity in placentas with and without intrauterine growth retardation.

BACKGROUND: Human telomerase reverse transcriptase has been found in telomerase-positive tumor tissues, but not in telomerase-negative nonmalignant somatic cells. METHODS: Thirty-two first-trimester chorionic villi specimens (Group A), 33 second- and third-trimester placenta specimens without asymmetric intrauterine growth retardation (Group B) and 13 specimens of placenta tissue from cases with intrauterine growth retardation (Group C) were examined for telomerase activity and expression of human telomerase reverse transcriptase by reverse transcription polymerase chain reaction and quantitative reverse transcription polymerase chain reaction. RESULTS: Telomerase activity was detected in 29 of the 32 specimens (90.6%) in Group A, in 20 of the 33 specimens (60.6%) in Group B and none of the 13 specimens (0.0%) in Group C. Human telomerase reverse transcriptase was identified in all 32 specimens of Group A (100%), all 33 specimens of Group B (100%) and 2 of the 13 specimens in Group C (15.4%) by nested reverse transcription polymerase chain reaction. Copy numbers of human telomerase reverse transcriptase were 202.3 +/- 73.0 (n=32), 8.8 +/- 2.9 (n=33) and 0 (n=13) in Groups A, B, and C, respectively. Significant differences were observed between Groups A and B, Groups A and C, and Groups B and C (p <0.01, p < 0.01, and p < 0.01, respectively). CONCLUSIONS: Our findings indicate that human telomerase reverse transcriptase expression is the rate-limiting determinant of telomerase activity in chorionic villi during the first trimester. Telomerase activity was not detected in placentas with intrauterine growth retardation, whereas human telomerase reverse transcriptase was expressed in some placentas with intrauterine growth retardation.

Chorionic Villi Sampling↗

High temporal resolution dynamic contrast MRI in a high risk group for placenta accreta.

Antenatal diagnosis of placenta accreta with MR is not easy even now because T2-weighted images (T2WI) cannot differentiate chorionic villi from decidua basalis. We performed dynamic contrast MRI to study whether trophoblastic villi could be separately demonstrated from the decidua basalis, and whether the contrast resolution between the placenta and myometrium could improve compared to T2WI. Six pregnant women with prior cesarean section were examined at 34-38 gestational weeks. Sagittal T2-weighted images with fast spin echo sequences and dynamic contrast studies with fast field echo sequence every 10-14 s after contrast injection were performed. We analyzed the enhancing pattern of the placenta and compared the contrast between placenta and myometrium. We reviewed medical records to identify complications during the placental delivery and the complications of their newborns. In the early phase after contrast enhancement, multiple foci of the strong lobular enhancement were observed in all cases. Other parts of placenta were slowly but strongly enhanced following them. We speculated that the former corresponded to intervillous space and the latter decidua basalis. The contrast between placenta and myometrium tended to be distinct near the inner cervical os on both T2WI and dynamic contrast study. On the other hand, it was indistinct in the upper part of the uterine body on T2WI despite it was clearly demonstrated on dynamic contrast study. The placentae were delivered without any complication in all cases. Although two neonates showed fetal distress, none of the infant remained any sequelae at the time of the discharge. The other four were well although one of them complicated with meconium staining. As dynamic contrast MRI can differentiate chorionic villi and decidua basalis, and can provide excellent contrast between placenta and myometrium at anywhere within the uterus, it may be a promising technique for antepartum diagnosis of the placenta accreta.

Chorionic Villi↗

The openings of uteroplacental vessels with villous infiltration at different gestational ages.

CONTEXT: The number of uteroplacental vessels flowing into the intervillous space in mature placentas has been reported in some studies to increase and in others to decrease. Both villous infiltration and proliferation in the vessels have been neglected in histologic examinations and need to be studied. OBJECTIVE: To clarify these conflicting findings regarding villous infiltration and proliferation in the uteroplacental vessels. DESIGN: A retrospective study was done using placental sections of different gestational ages. The openings of the vessels in each section were counted, noting if they were with or without villous infiltration. The frequency of openings per section was calculated, and the findings were grouped by gestational age. RESULTS: The frequency of total openings was significantly lower in the 41 to 37 weeks group (1.2) than in the 36 to 30 weeks group (2.0), the 29 to 20 weeks group (2.2), and the 19 to 13 weeks group (2.4) (P < .001). The frequency of openings with villous infiltration decreased similarly in mature placentas. Chorionic villi infiltrated the openings and proliferated in uteroplacental vessels. Differentiation between arteries and veins was difficult in the basal plate, because all vessels had veinlike structures. CONCLUSIONS: This decreasing frequency of openings in mature placentas suggests that the amount of intervillous blood flow is limited in full-term and postterm pregnancy. Villous infiltration into the vessels is considered a normal finding with gestation and can provide trophoblast for uteroplacental arteries. The relationship between placental development and villous proliferation in the vessels is presented.

Chorionic Villi↗

Placental expression of estrogen receptor beta and its hormone binding variant--comparison with estrogen receptor alpha and a role for estrogen receptors in asymmetric division and differentiation of estrogen-dependent cells.

During human pregnancy, the production of 17-beta-estradiol (E2) rises steadily to eighty fold at term, and placenta has been found to specifically bind estrogens. We have recently demonstrated the expression of estrogen receptor alpha (ER-alpha) protein in human placenta and its localization in villous cytotrophoblast (CT), vascular pericytes, and amniotic fibroblasts. In vitro, E2 stimulated development of large syncytiotrophoblast (ST) aggregates. In the present study we utilized ER-beta affinity purified polyclonal (N19:sc6820) and ER-alpha monoclonal (clone h-151) antibodies. Western blot analysis revealed a single approximately 52 kDa ER-beta band in chorionic villi (CV) protein extracts. In CV, strong cytoplasmic ER-beta immunoreactivity was confined to ST. Dual color immunohistochemistry revealed asymmetric segregation of ER-alpha in dividing villous CT cells. Prior to separation, the cell nuclei more distant from ST exhibited high ER-alpha, while cell nuclei associated with ST showed diminution of ER-alpha and appearance of ER-beta. In trophoblast cultures, development of ST aggregates was associated with diminution of ER-alpha and appearance of ER-beta immunoreactivity. ER-beta was also detected in endothelial cells, amniotic epithelial cells and fibroblasts, extravillous trophoblast (nuclear and cytoplasmic) and decidual cells (cytoplasmic only). In addition, CFK-E12 (E12) and CWK-F12 (F12) monoclonal antibodies, which recognize approximately 64 kDa ER-beta with hormone binding domain, showed nuclear-specific reactivity with villous ST, extravillous trophoblast, and amniotic epithelium and fibroblasts. Western blot analysis indicated abundant expression of a approximately 64 kDa ER-beta variant in trophoblast cultures, significantly higher when compared to the chorionic villi and freshly isolated trophoblast cell protein extracts. This is the first report on ER-beta expression in human placenta and cultured trophoblast. Our data indicate that during trophoblast differentiation, the ER-alpha is associated with a less, and ER-beta with the more differentiated state. Enhanced expression of approximately 64 kDa ER-beta variant in trophoblast cultures suggests a unique role of ER-beta hormone binding domain in the regulation of trophoblast differentiation. Our data also indicate that asymmetric segregation of ER-alpha may play a role in asymmetric division of estrogen-dependent cells.

Amnion↗

First-trimester diagnosis of late-infantile neuronal ceroid lipofuscinosis (LINCL) by tripeptidyl peptidase I assay and CLN2 mutation analysis.

Late-infantile neuronal ceroid lipofuscinosis (LINCL) is a progressive neurodegenerative disorder caused by the deficiency of lysosomal tripeptidyl peptidase I (TPP-I) encoded by the CLN2 gene. We report the first case of early prenatal diagnosis of LINCL by combined enzyme and mutation analysis. TPP-I activity in chorionic villi (CV) was less than 2% of the mean normal control level and g.1946A > G and g.3670C > T mutations were demonstrated, as in the two previously affected children. After termination of pregnancy, TPP-I deficiency was confirmed in cultured CV cells and in the fetal skin fibroblasts. The expression of unequivocal TPP-I deficiency in CV demonstrates that enzyme assay is a reliable option for prenatal diagnosis of LINCL.

Aminopeptidases↗

First trimester diagnosis of methylmalonic aciduria.

We have studied methylmalonyl CoA mutase activity in control chorionic villi to establish the potential use of assays performed directly on this tissue for prenatal diagnosis of methylmalonic aciduria. We report the detection of a fetus affected with the apo-mutase deficient form of this condition at 9 weeks' gestation. Methylmalonyl CoA mutase was markedly deficient in chorionic villi, approximately 2.5 per cent of the mean control value. However, incorporation of label from [14C]-propionate into protein was 10 and 40 per cent of the mean control value, respectively, in two portions of the same biopsy, highlighting potential problems in the use of this indirect assay. Normal results were obtained in chorionic villus samples from four other pregnancies 'at risk' for methylmalonic aciduria which were subsequently shown to be unaffected with this condition. The diagnosis in the affected pregnancy was confirmed by demonstration of a marked deficiency of methylmalonyl CoA mutase activity in villi obtained at termination and in cultured fetal fibroblasts. Reduced incorporation of [14C]-propionate label into protein was also found in these tissues.

Amino Acid Metabolism, Inborn Errors↗

Chromosome abnormalities detected in chorionic villus biopsies of failing pregnancies in a subfertile population.

OBJECTIVE: To determine the range and prevalence of chromosomal abnormalities occurring in failing pregnancies in subfertile women. DESIGN: Prospective biochemical and ultrasound monitoring of all pregnancies conceived between 1988 and 1990 in a subfertile population. SETTING: A single-centre specialist fertility clinic in Perth, Western Australia. SUBJECTS: Tissue from 50 early pregnancy losses was successfully cultured for chromosomal analysis from 46 pregnancies comprising 29 anembryonic pregnancies, 9 miscarriages and 8 ectopic pregnancies. MAIN OUTCOME MEASURES: Impending pregnancy loss was identified at an early stage. Chromosomal analysis was performed on chorionic villi obtained before the diagnosis became clinically evident. RESULTS: Significant chromosomal abnormalities were identified in 54% (14/26) of early pregnancy losses where gamete manipulation was involved and 45% (9/20) of those following spontaneous conception. The most common abnormalities were trisomies (12 pregnancies, mainly trisomy 16), triploidies (3 pregnancies) and monosomy X (3 pregnancies). An excess of female fetuses was noted with only 24% of conceptuses (11/46) bearing a Y chromosome. CONCLUSIONS: The data indicate a similar rate of chromosomal abnormalities underlying pregnancy losses at earlier stages of pregnancy and after infertility treatments as that reported from the general population. Gamete manipulation does not appear to confer a higher rate of chromosomal abnormalities in ensuing pregnancies.

Adult↗

Chorionic villus culture for prenatal diagnosis of chromosome defects: reduction of the long-term cultivation time.

We report in detail two series of chorionic villus cultivation for prenatal chromosomal diagnosis. Chorionic villi were sampled from both first- and second-trimester pregnancies. One hundred cultures were treated with trypsin-EDTA for 2 h and collagenase overnight, (method A) and 100 were treated with trypsin-EDTA for 1 h and collagenase for 2 h (method B). Using short-term enzymatic digestion, the cultivation time was reduced from 14 days to 6 days. Sufficient amounts of metaphases of good quality were present in 93 per cent of primary cultures harvested in situ, whereas enough metaphases of sufficiently good quality were in most cases present only after subcultivation of the cultures using method A. The decrease in cultivation time obtained is probably due to a higher yield of viable cells in monocellular suspension, an increased attachment efficiency, and a more rapid attachment of single cells (within 24 h).

Chorionic Villi↗

Rapid detection of numerical aberrations of chromosomes 13, 18 and 21 in chorionic mesenchymal cells.

We have devised and evaluated a rapid screening method for the detection of numerical aberrations of chromosomes 13, 18 and 21 in chorionic villus cells. We used non-radioactive in situ hybridization (ISH) with three chromosome-specific probes on overnight-attached mesenchymal cells from chorionic villi. A blind study was performed of 47 karyotypically normal samples, one triploid sample, two samples trisomic for chromosome 21, and two samples from a fetus with putative mosaicism (46/47, +21). All samples were hybridized with the chromosome 18- and 21-specific probes. Thirty samples were additionally hybridized with the chromosome 13-specific probe. The test could be completed within 3-4 days of sampling. In samples disomic with respect to the probed chromosomes, an average of 2 per cent (range 0-9 per cent) had three hybridization signals. By contrast, in the samples trisomic for the probed chromosome(s), 57 per cent (chromosome 13), 51 per cent (chromosome 18), and an average of 74 per cent (55-86 per cent) (chromosome 21) of the nuclei exhibited three signals. In the putative mosaic samples, the number of nuclei with three chromosome 21-specific signals ranged from 41 to 69 per cent. We conclude that this technique rapidly and clearly distinguishes between normal and trisomic/triploid samples, and consequently may be of use in future prenatal diagnosis.

Chorionic Villi↗

[Subjective experience of prenatal diagnosis and genetic counseling].

Two surveys (one involving 650, the other 638 women) based upon interviews about the utilization of prenatal diagnosis by clients are reported. First it is demonstrated which factors obstruct a decision for prenatal diagnosis. Then, a contrast is made between the risk attitude of two groups, namely women who underwent amniocentesis or chorion villi biopsy and those respondents who decided against prenatal diagnosis. Finally, how the examination technique (amniocentesis or chorion villi biopsy) influences the experience of pregnancy is discussed.

Adaptation, Psychological↗

The value of frozen section Pipelle endometrial biopsy as an outpatient procedure in the diagnosis of ectopic pregnancy.

This is a prospective study evaluating 28 patients who were suspected to have ectopic pregnancy. Frozen section Pipelle endometrial biopsy was performed as an outpatient procedure to look for the presence of chorionic villi in the specimen. The sensitivity of the frozen section endometrial biopsy in detecting the presence of chorionic villi was 13.3% and the specificity was 100%. The positive predictive value was 100% and the negative predictive value was 50%. We concluded that frozen section endometrial biopsy was not helpful in predicting intrauterine gestational process; therefore, it has a limited application in patients suspected to have ectopic pregnancy.

Ambulatory Surgical Procedures↗

Discrepant karyotypes after second- and third-trimester combined placentacentesis/amniocentesis.

Cytogenetic data are presented from a total of 1306 consecutive pregnancies with successful diagnosis obtained from both chorionic villi after short-time culture (CVS-SC) and amniotic fluid cell cultures (AC); samples had been taken simultaneously at combined placentacentesis (placental biopsy) and amniocentesis during the second (92.8 per cent) and third (7.2 per cent) trimesters. Concordant results were obtained in 1218 pregnancies with a normal karyotype and in 62 pregnancies with an aberrant fetal karyotype. Discrepant, i.e. false-positive and false-negative, results were found in 26 cases (2 per cent). From these data the accuracy of CVS-SC, defined as the proportion of all correct diagnoses, is calculated to be 98 per cent. Three non-mosaic and 14 mosaic false-positive results obtained after CVS-SC could not be confirmed by AC. Related to 1235 true normal fetal karyotypes, the specificity of CVS-SC, i.e. the proportion of normal karyotypes correctly diagnosed, amounts to 98.6 per cent. In nine pregnancies, an aberrant fetal karyotype detected after AC was missed by CVS-SC. The sensitivity of CVS-SC, i.e. the proportion of abnormal fetuses correctly diagnosed (62 out of 71), amounts to 87.3 per cent in our study group.

Amniocentesis↗

[Postnatal and prenatal diagnosis of mucopolysaccharidosis type II (Hunter syndrome)].

OBJECTIVE: Mucopolysaccharidosis type II (MPS II, Hunter syndrome, OMIM 309900) is an X-linked recessive lysosomal storage disease resulting from a deficiency of iduronte-2-sulphate sulphatase (IDS). The present study aimed to establish an enzyme assay method for IDS activity for carrying out postnatal and prenatal diagnosis of MPS II by means of IDS activity assay on plasma, uncultured chorionic villi (CV) and cultured amniotic fluid cells (AF cell) using a new synthesized substrate. METHODS: A fluorigenic substrate (4-methylumbelliferyl-alpha-iduronate-2-sulphate, MU-alpha-Idu-2S) was used for the assay of IDS activity. IDS activity in plasma was determined for diagnosis of the proband. Prenatal diagnosis in 10 pregnancies at risk was carried out according to IDS activity on uncultured CV at 11th week or on cultured AF cell at 18th week of gestation. At the same time, IDS activity was also determined in the maternal plasmas to observe the change of IDS activity in pregnancy. The fetal sex determination was performed by PCR amplification of the ZFX/ZFY genes. RESULT: The IDS activity in plasma of normal controls and obligate heterozygotes were 240.2 - 668.2 nmol/(4 hxml) and 88.7 - 547.9 nmol/(4 hxml), respectively, while the enzyme activities in plasmas were in the range of 0.3 - 18.6 nmol/(4 hxml) in affected male. The IDS activities were 37.2 - 54.9 nmol/(4 hxmg protein) and 21.4 - 74.4 nmol/(4 hxmg protein) in CV and cultured AF cells respectively. Out of 50 suspected cases, 46 were diagnosed as having MPS II and 4 were excluded. Prenatal diagnosis was performed on 10 pregnancies at risk. Four of 5 male fetuses [IDS activity were 4.7, 1.8, 7.0 nmol/(4hxmg protein) in CV, 0.6 nmol/(4 hxmg protein) in AF cell] were diagnosed as having MPS II and the other 5 fetuses were normal females [IDS activity were: 48.7, 5.9, 25.2 nmol/(4 hxmg protein) in CV, 55.2, 40.9 nmol/(4 hxmg protein) in AF cell]. Increased IDS activity was observed in plasma of the pregnant women with unaffected fetuses, while the IDS activity decreased in pregnancies with affected fetuses. IDS activity of one female fetus was very low [5.9 nmol/(4 hxmg protein)], but the IDS activity in maternal plasmas increased, this fetus was a normal female. CONCLUSIONS: The method using a synthesized fluorigenic 4-methylumbelliferyl-substrate was a sensitive, rapid and convenient assay of IDS activity and was reliable for early prenatal diagnosis. Determination of fetal sex would be helpful in excluding the female fetus with low IDS activity from being considered as an affected male fetus. It would be further helpful if IDS activity in maternal plasma was taken into account.

Amniotic Fluid↗

[Submicroscopic detection of oriented protein filaments in the plasmoditrophoblast of the human placenta (author's transl)].

In this paper is described by histochemical, polarization optical and electron microscopical techniques resp. an up to now unknown protein structure in the basal plasmoditrophoblast of the human placenta. This structure consists of noncollagenic filaments containing cystin or cystein. They are arranged in the plain in the form of a network and parallel to the surface of the chorionic villi. They occur in connection with Langhans cells, they regularly existed in young placentas, where they completely surround the chorionic villi, and they occur in the villi of termborn placentas only incomplete in parts of the plasmoditrophoblast. Differences of the molecular structure of the network of protein filaments, which are depended on the age, are not demonstrable.

Chorion↗

[Distribution of the concentrations of angiotensin II (A II), A II receptors, hPL, prolactin, and steroids in human fetal membranes].

By analyzing human trophoblastic tissues at the full term of pregnancy, this study shows the highest levels of angiotensin-II (729 +/- 111 and 602 +/- 105 pg/g of tissue), angiotensin-II receptors (295 +/- 30 and 250 +/- 32 fmol/mg proteins), human placental lactogen (973 +/- 154 and 680 +/- 28 micrograms/g) and progesterone (1,501 +/- 193 and 1,070 +/- 151 ng/g) in chorionic villi and in placental basal plate respectively. Tissue values of angiotensin-II, hPL and Progesterone were 4 times superior to those obtained in amniotic fluid and in umbilical and maternal blood. Estradiol values in chorionic villi were similar to those in placental basal plate, in chorionic plate and in chorion, but significantly higher (p less than 0,001) than in amnion, amniotic fluid and in umbilical and maternal blood. The concentrations of prolactin in chorion were 3 times superior than those found in amnion, in placental tissue, in amniotic fluid and in umbilical and maternal blood. A positive correlation was observed between Angiotensin-II and its receptors and also with hPL, P4/hPL ratio and E2/P4 ratio. Thus, angiotensin-II could play an important role in the physiology of pregnancy, due to its vasopressive action and due to its interactions with other peptides and chorio-placental steroids.

Angiotensin II↗

Etiology and pathology of equine placentitis.

Placentas from aborted, stillborn, and premature foals were examined during the 1988 and 1989 foaling seasons, and 236 of 954 (24.7%) had placentitis. Microorganisms associated with placentitis were isolated or demonstrated from 162 of 236 (68.6%) placentitis cases. Leptospira spp. and a nocardioform actinomycete were 2 important, newly emerging bacteria associated with equine placentitis. Major pathogens identified in decreasing order were Streptococcus zooepidemicus, Leptospira spp., Escherichia coli, a nocardioform actinomycete, fungi, Pseudomonas aeruginosa, Streptococcus equisimilis, Enterobacter agglomerans, Klebsiella pneumoniae, and alpha-hemolytic Streptococcus. Pathogens were not recovered in 64 cases (27.1%) and overgrowth by saprophytic bacteria was recorded in 10 cases (4.2%). Twenty-seven cases (16.6%) had mixed bacterial growth and 93 cases (57.4%) had bacteria cultured from both placenta and fetal organs. The majority of the placentitis cases caused by bacteria, with the exception of Leptospira spp. and the nocardioform actinomycete, occurred in 2 forms. One was acute, focal or diffuse; had an infiltration of neutrophils in the intervillous spaces or necrosis of chorionic villi; was associated with bacteremia; and frequently occurred in the placenta from fetuses expelled before or at midgestation. The other was observed from foals expelled at late gestation, was mostly chronic and focal or focally extensive, and occurred mostly at the cervical star area. Chronic placentitis was characterized by the presence of 1 or a combination of the following lesions: necrosis of chorionic villi, presence of eosinophilic amorphous material on the chorion, and infiltration of mononuclear inflammatory cells in the intervillous spaces, villous stroma, chorionic stroma, vascular layer, and allantois.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Veterinary↗