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PubMed2005

Induction of cytochrome P450 isozymes by phenobarbital in pregnant rat and fetal livers and placenta.

Cytochrome P450 (CYP) isozymes are important in metabolizing xenobiotics. They are found in extrahepatic tissues such as placenta as well as liver. Previously, we reported that CYP3A1 was detected in the cytoplasm of giant cells in the trophoblastic region of placenta of rats through pregnancy. In this study, we examined the changes in the expression of CYP proteins in the pregnant rat and fetal livers and placenta after treatment with phenobarbital (PB), one of the antiepileptic drugs which is well known to induce several phase I and phase II drug metabolizing enzymes in the liver. Namely, F344 pregnant rats were treated with PB (80 mg/kg, i.p.) from 13 days of gestation (DG) to 16 DG. All animals were sacrificed on 17 DG, and Western blot analysis and immunohistochemical staining on nine CYP proteins (CYP1A1, CYP2B1, CYP2C6, CYP2C12, CYP2D1, CYP2D4, CYP2E1, CYP3A1, and CYP4A1) and histological examination were done in the dam's liver, placenta, and the fetal liver. Western blot analysis revealed that CYP3A1 protein was significantly induced, CYP2B1 protein was detected, and CYP2D1 protein was significantly decreased in the dam's liver after PB-treatment. In placenta, only CYP3A1 was detected with no difference between control and PB-treated animals. The results of immunohistochemical staining corresponded closely to those of Western blot analysis in the dam's liver and placenta. In the fetal liver, CYP3A1 and CYP2C6 proteins were significantly induced after the PB-treatment, but their immunostainability was not prominent. The present results are considered useful as a basis for further investigation of drug metabolism in pregnant animals.

Animals↗
PubMed2004

PLET1 (C11orf34), a highly expressed and processed novel gene in pig and mouse placenta, is transcribed but poorly spliced in human.

Sequencing of porcine cDNAs identified a novel EST with high frequency in placenta tissue. Full-length PLET1 (placenta-expressed transcript 1, also called C11orf34) matched a mouse cDNA and many bovine and mouse ESTs but no human transcripts or ESTs. However, the porcine cDNA matched several putative exons within a human genomic DNA fragment on chromosome 11. This human locus is in a region of conserved synteny with pig chromosome 9, to which the porcine gene was subsequently mapped. RNA blot hybridization showed that this gene had high expression in porcine and mouse conceptus and throughout placenta development. In situ hybridization using mouse placenta showed PLET1 expression in trophoblast cells of the labyrinth, as well as in spongiotrophoblast and glycogen trophoblast cells. However, no expression of PLET1 was detected by RNA blot analysis of human placenta, although RT-PCR analysis detected very small amounts of partially spliced RNA that were significantly less abundant than the RNA levels in mouse placenta. Donor and acceptor splicing site sequences in the exons of the human gene are poorly conserved and may be the cause of inefficient splicing found specifically in human tissue. Our data correct GenomeScan annotation of this region of the human genome and describe functional gene discovery in mammals not recognized in human EST projects.

Amino Acid Sequence↗
PubMed1993

The epidemiology of placenta previa in the United States, 1979 through 1987.

OBJECTIVE: Placenta previa can cause serious, occasionally fatal complications for fetuses and mothers; however, data on its national incidence and sociodemographic risk factors have not been available. STUDY DESIGN: We analyzed data from the National Hospital Discharge Survey for the years 1979 through 1987 and from the Retrospective Maternal Mortality Study (1979 through 1986). RESULTS: We found that placenta previa complicated 4.8 per 1000 deliveries annually and was fatal in 0.03% of cases. Incidence rates remained stable among white women but increased among black and other minority women (p < 0.1). In addition, the risk of placenta previa was higher for black and other minority women than for white women (rate ratio 1.3, 95% confidence interval 1.0 to 1.7), and it was higher for women > or = 35 years old than for women <20 years old (rate ratio 4.7, 95% confidence interval 3.3 to 7.0). Women with placenta previa were at an increased risk of abruptio placentae (rate ratio 13.8), cesarean delivery (rate ratio 3.9), fetal malpresentation (rate ratio 2.8), and postpartum hemorrhage (rate ratio 1.7). CONCLUSION: Our findings support the need for improved prenatal and intrapartum care to reduce the serious complications and deaths associated with placenta previa.

Adult↗
PubMed1992

Comparative analysis of normal and growth-retarded placentas with phosphorus nuclear magnetic resonance spectroscopy.

OBJECTIVE: Phosphorus 31 magnetic resonance spectroscopy studies were carried out on placentas from normal vaginal and elective cesarean deliveries without antenatal complications and from pregnancies complicated by intrauterine growth retardation of unknown cause to determine differences. STUDY DESIGN: Perchloric acid extraction was performed on frozen tissue, and quantitative analysis was carried out for well-resolved resonances representing adenosine triphosphate, sugar phosphate, inorganic phosphorus, diphosphoglycerate, glycerophosphorylethanolamine, and glycerophosphorylcholine. RESULTS: Adenosine triphosphate levels were highest in the growth-retarded group. There were significantly higher levels of sugar phosphate, diphosphoglycerate, and glycerophosphorylcholine in the placentas of the growth-retarded pregnancies compared with those from normal placentas. CONCLUSION: These differences may represent a response to hypoxia and an increase in the amount of blood in the placenta. The results demonstrate the utility of nuclear magnetic resonance spectroscopy for studying the pathology of abnormal placentas to gain a better understanding of the pathology and represent early steps toward in vivo spectroscopic studies of the placenta.

Cesarean Section↗
PubMed1996

Management of the symptomatic placenta previa: a randomized, controlled trial of inpatient versus outpatient expectant management.

OBJECTIVE: Our purpose was to determine the safety, efficacy, and costs of inpatient and outpatient management of symptomatic placenta previa. STUDY DESIGN: Fifty-three women with the initial diagnosis of placenta previa at 24 to 36 weeks' gestation who required hospitalization for vaginal bleeding were stabilized and then randomized to receive either inpatient or outpatient expectant management. Twenty-seven inpatients were placed at bed rest with minimal ambulation, received weekly corticosteroids until 32 weeks of gestation, and underwent ultrasonographic examination at 2-week intervals to assess fetal growth and placental location. Twenty-six outpatients were discharged home after > or = 72 hours of hospitalization. Each week they also received corticosteroids, until 32 weeks' gestation, and ultrasonographic evaluations. Outpatients with recurrent bleeding were readmitted for evaluation. All subjects who reached 36 weeks' gestation with persistent placenta previa underwent amniocentesis. When fetal lung maturity was present, cesarean delivery was electively performed. RESULTS: There were insignificant differences between inpatients and outpatients for mean age, parity, race, type of previa (complete or partial), number of prior vaginal bleeding episodes, and initial hemoglobin value. The mean estimated gestational age at enrollment was 29.1 +/- 3.1 (SD) weeks for inpatients and 29.9 +/- 3.1 weeks for outpatients. In eight patients the placenta was found to no longer cover the internal os by 36 weeks' gestation. There were seven patients in each group who did not complete the protocol for initial treatment assignment. The average estimated gestational age at delivery for the inpatients was 34.5 +/- 2.4 weeks and 34.6 +/- 2.3 weeks for the outpatients (p = 0.90), whereas the mean birth weights were 2413.7 +/- 642.7 gm and 2607.8 +/- 587.1 gm, respectively (p = 0.28). Thirty-three patients (62.3%) had recurrent episodes of bleeding, with 26 requiring expeditious cesarean delivery. Four (14.8%) inpatients and one (3.7%) outpatient required blood transfusion (p = 0.67). There was no difference in neonatal morbidity (defined as the presence of respiratory distress syndrome, intracranial hemorrhage, or culture-proved sepsis) between the two groups (relative risk 1.16, 95% confidence interval 0.66 to 2.02). There were no neonatal deaths. The mean number of maternal hospital days differed significantly between the two groups: inpatients required an average of 28.6 +/- 20.3 days and outpatients remained hospitalized for an average of 10.1 +/- 8.5 days (p < 0.0001). Cost analysis based on maternal hospital days reveals a net savings of +15,080 per patient if women with symptomatic placenta previa initially diagnosed before 37 weeks' gestation are treated as outpatients. CONCLUSIONS: For selected patients, outpatient management of symptomatic placenta previa appears to be an acceptable alternative to traditional conservative expectant inpatient management.

Adult↗
PubMed1999

Placenta previa: a 22-year analysis.

OBJECTIVE: Our purpose was to identify what anesthetic method is safer for women with a placenta previa. STUDY DESIGN: We retrospectively reviewed all women with placenta previa who underwent cesarean delivery during the period January 1, 1976-December 31, 1997 at Northwestern Memorial Hospital. RESULTS: Of 93,384 deliveries, placenta previa was found in 514 women. Identifiable trends with time included an increasing incidence of placenta previa (r = 0.54, P <.01); cesarean hysterectomy (r = 0.54, P <.01); placenta accreta (r = 0.45, P <.03); and regional anesthesia (r = 0.84, P <.0001). The mean gestational age at delivery was 35.3 +/- 3.4 weeks and did not change with time. General anesthesia was used for delivery in 380 women and regional anesthesia was used for 134 women. Prior cesarean delivery and general anesthesia were independent predictors of the need for blood transfusion, but only prior cesarean delivery was a predictor of the need for hysterectomy. General anesthesia increased the estimated blood loss, was associated with a lower postoperative hemoglobin concentration, and increased the need for blood transfusion. Elective and emergent deliveries did not differ in estimated blood loss, in postoperative hemoglobin concentrations, or in the incidence of intraoperative and anesthesia complications. Regional and general anesthesia did not differ in the incidence of intraoperative and anesthesia complications. CONCLUSIONS: In women with placenta previa, general anesthesia increased intraoperative blood loss and the need for blood transfusion. Regional anesthesia appears to be a safe alternative.

Adult↗
PubMed1999

Creatine kinase as a biochemical marker in diagnosis of placenta increta and percreta.

We describe 1 case of placenta increta and 1 of placenta percreta, both associated with elevated maternal serum creatine kinase concentration. In patients with placenta previa and ultrasonographic findings of an abnormally adherent placenta, an unexplained elevation in maternal serum creatine kinase level should alert the clinician to the possibility of placenta increta or placenta percreta, with an attendant increase in maternal morbidity.

Adult↗
PubMed2000

Toxic and essential elements in placentas of Swedish women.

OBJECTIVES: To evaluate interactions between toxic and essential elements in the mother-fetus relationship and possible predictors of trace element concentrations in placenta and cord blood. DESIGN AND METHODS: A group of 106 Swedish women was investigated for concentrations of cadmium, lead, and several essential elements in placenta as well as cadmium, lead, zinc, and selenium in venous blood collected at gestational week (gw) 36 and umbilical cord blood. Relations between these elements and maternal and child's characteristics were examined. RESULTS: The concentrations of cadmium in placenta ranged from 10 to 170 nmol/kg, with the median value (Md) being 46 nmol/kg. Cord blood cadmium (Md of 0.19 nmol/L) was only about 10% of that in maternal blood. Smokers had significantly higher cadmium concentrations in blood (p < 0.001) and placenta (p = 0.001) than non-smokers. The median placental concentration of lead was 26 nmol/kg (range 0-630 nmol/kg). The lead levels in cord blood (Md of 54 nmol/L) were almost the same as in maternal blood. Statistically significant negative associations were found between cord blood lead, on one hand, and child's weight, length, and head circumference, on the other. The placental levels (medians and ranges) of the essential elements (micromol/kg) were 160 (120-280) for zinc, 2.4 (2.0-3.3) for selenium, 15 (10-20) for copper, 0.084 (0.02-0.32) for cobalt, 0.055 (0.03-0.12) for molybdenum, and 1.2 (0. 65-5.1) for manganese, respectively. Several of the essential elements in placenta correlated significantly with each other. Multiparous mothers had significantly lower concentrations of zinc (p = 0.002) and selenium (p = 0.049) in serum as well as zinc (p = 0. 001) and calcium (p = 0.004) in placenta than nulliparous ones. Also, cord blood zinc decreased with parity. CONCLUSIONS: The results showed that lead, but not cadmium crossed easily the placental barrier. There were no negative effects of cadmium on the zinc status. Cord blood lead, on the other hand, was a negative predictor of child's birth weight, length and head circumference, indicating that lead might have negative influence on growth in children even at very low exposure levels. There was a depletion of maternal stores of essential elements with increasing parity.

Cadmium↗
PubMed2001

Apoptosis in the placenta of pregnancies complicated with IUGR.

OBJECTIVE: In this study we have investigated the presence of apoptosis in the placental tissue of pregnancies complicated with intra-uterine growth restriction (IUGR). METHOD: Placental samples were obtained from 22 normal third trimester pregnancies and 20 pregnancies complicated with IUGR. The criteria for fetal growth impairment were clinical evidence of sub-optimal growth, ultrasonographic demonstration of deviation from normal percentiles of growth and birth weight under 10th percentile. Terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling (TUNEL) staining was used to demonstrate the apoptotic cells in all samples. Student-t, Mann-Withney U-test, Fisher exact test and Spearman correlation were used for statistical analysis. RESULTS: We detected apoptosis in 10 placentas in the study group vs. none in the control group. Placentas from pregnancies complicated with IUGR demonstrated 0.12% (0.1%-0.4%) apoptotic cells. The rate of apoptotic cells in the placenta was significantly higher in pregnancies complicated with IUGR than normal uncomplicated pregnancy (P=0.0019). Apoptosis were more abundant in the trophoblasts, especially cytotrophoblasts, in the placenta. We could not find a correlation between the apoptosis in the placenta of pregnancies complicated with IUGR and birth weight, multi-parity, gestational age, birth weight percentile and mode of delivery (C/S vs. vaginal delivery). CONCLUSION: We believe that the increased number of apoptosis in the placenta of pregnancies complicated with IUGR may have an important compensatory role to transmit nutrition and gas exchange easily to the fetus.

Adult↗
PubMed2003

The relationship of placenta previa and history of induced abortion.

OBJECTIVES: We evaluated the risk of placenta previa being associated with a history of induced abortion by different surgical procedures. METHODS: Cases (n=192) were women who had a singleton delivery complicated by placenta previa at a major obstetric care hospital in western Washington state between April 1, 1990 and December 31, 1992. Controls (n=622) were women with singleton deliveries not complicated by placenta previa or abruption. Odds ratios, determined by logistic regression, approximate the relative risks. RESULTS: Vacuum aspiration abortion was not associated with an increased risk of placenta previa (OR 0.9, 95% CI 0.6-1.5). However, the risk of placenta previa increased with the number of sharp curettage abortions (OR 2.9, 95% CI 1.0-8.5 for > or =3). CONCLUSIONS: Risk of placenta previa may be increased in a dose response fashion by multiple sharp curettage abortions. However, vacuum aspiration does not confer an increased risk, and may be a better alternative.

Abortion, Induced↗
PubMed1998

Transport and endogenous release of vitamin B12 in the dually perfused human placenta.

The kinetics for vitamin B12, cobalamin (Cbl), transfer across the human placenta, and the retention of the endogenous Cbl and its release into the maternal and fetal compartments were investigated in a dually perfused human term placenta in vitro. After 4 hours of perfusion following a single bolus injection (peak maternal perfusate 94 fmol/ml) of 57Co-Cbl into the maternal reservoir, the maternal [57Co-Cbl] rapidly decreased whereas the fetal [57Co-Cbl] was only 9% of the final maternal [57Co-Cbl]. Even though there was a limited transfer of 57Co-Cbl to the fetus, the placenta rapidly accumulated Cbl. At 4 hours, 18% of the initial 57Co-Cbl dose was in the placenta; only 3% of the initial dose was in the fetal perfusate. Also after 4 hours, [57Co-Cbl] was bound > 95% to transcobalamin (TC)I/III-like proteins in the maternal perfusate, whereas Cbl was bound to TCI/III- and TCII-like proteins with some free in the fetal perfusate. In the cytosol, > 95% of the [57Co-Cbl] was bound (80% to TCII-like and 19% to TCI/III-like proteins). When no exogenous Cbl was added, total endogenous [Cbl] in the maternal circulation increased with time during 8 hours of perfusion at a rate of 0.25 +/- 0.12 pmol/gm per hour. Only 2% of this Cbl was free, whereas 98% was bound to specific binding proteins. Neither plateau values nor equilibration with the fetal side were noted. In the fetal circulation, there was a release of Cbl at a rate of 0.015 +/- 0.003 pmol/gm per hour, which was 99.99% bound. Thus the human placenta rapidly concentrates Cbl in the perfused lobule with little distribution of Cbl to nonperfused areas. Therefore, the human placenta modulates the asymmetric transfer of vitamin B12 on the basis of release of specific Cbl-binding proteins (TCI/III- and TCII-like) into the maternal and fetal perfusates.

Female↗
PubMed1985

Ultrastructure of the full-term shark yolk sac placenta. I. Morphology and cellular transport at the fetal attachment site.

During ontogeny, the yolk sac of some viviparous sharks differentiates into a yolk sac placenta that persists to term. The placenta is non-invasive and non-deciduate. Hematrophic transport is the major route of nutrient transfer from mother to fetus. The placental unit consists of: (1) an umbilical stalk; (2) the smooth, proximal portion of the placenta; (3) the distal, rugose portion; (4) the egg envelope; and (5) the maternal uterine tissues. Exchange of metabolites is effected through the intervening egg envelope. The distal rugose portion of the placenta is the fetal attachment site. It consists of: (1) surface epithelial cells; (2) a collagenous stroma with vitelline capillaries; and (3) an innermost boundary cell layer. The columnar surface epithelial cells are closely apposed to the inner surface of the egg envelope. Wide spaces occur between the lateral margins of adjacent cells. Surface epithelial cells contain an extensive apical canalicular-tubular system and many whorl-like inclusions in their basal cytoplasm. Capillaries of the vitelline circulation are closely situated to these cells. A well-developed collagenous stroma separates the surface epithelium from an innermost boundary cell layer. In vitro exposure of full-term placentae to solutions of trypan blue and horseradish peroxidase (HRP) reveals little uptake by the smooth portion of the placenta but rapid absorption by the surface epithelial cells of the distal, rugose portion. HRP enters these cells by an extensive apical system of smooth-walled membranous anastomosing canaliculi and tubules. Prominent whorl-like inclusions that occupy the basal cytoplasm of the surface cells, adjacent to the pinocytotically active endothelium of the vitelline capillaries, are hypothesized to be yolk proteins that are transferred from the mother to embryo throughout gestation.

Animals↗
PubMed2002

The likelihood of placenta previa with greater number of cesarean deliveries and higher parity.

OBJECTIVE: To examine the relationship between prior cesarean delivery and placenta previa. METHODS: A hospital-based, case-control study was conducted in which 316 multiparous women with placenta previa were identified. Controls consisted of 2051 multiparous women with spontaneous vaginal deliveries. Information on prior cesarean delivery was examined in three forms: as a dichotomous variable, as an ordinal variable, and as a set of three indicator variables for one, two, and three or more cesarean deliveries. Multivariable logistic regression modeling was used to obtain an adjusted estimate of this association. RESULTS: Women with a prior cesarean delivery were more likely to have a placenta previa than those without (odds ratio [OR] 1.59, 95% confidence interval [CI] 1.21, 2.08). The likelihood of placenta previa increased as both parity and number of cesarean deliveries increased. Thus, the adjusted OR for a primiparous woman with one cesarean delivery was 1.28 (95% CI 0.82, 1.99). For a woman who has four or more deliveries with only a single cesarean delivery, the OR increases to 1.72 (95% CI 1.12, 2.64). This trend continues with greater parity and a greater number of cesarean deliveries such that the likelihood of placenta previa for a woman with parity greater than four and greater than four cesarean deliveries was OR 8.76 (95% CI 1.58, 48.53). CONCLUSION: This study supports the association between prior cesarean delivery and placenta previa and demonstrates that the joint effect of parity and prior cesarean delivery is greater than that of either variable alone.

Adult↗
PubMed2002

Placenta accreta postpartum.

BACKGROUND: Placenta accreta is the abnormal attachment of the placenta to the uterus. It occurs when the decidua basalis is either absent or incomplete. It is uncommon and most often presents with a retained placenta and hemorrhage. CASE: A 29-year-old gravida 1 had an uncomplicated antenatal course and delivery. The third stage of labor was complicated by a retained placenta necessitating manual removal. Her postpartum course was complicated by a persistent endometritis. The diagnosis of placenta accreta was made with the help of sonohysterography. CONCLUSION: Sonohysterography is a useful tool in discriminating a solid intracavitary mass from a placenta accreta postpartum.

Adult↗
PubMed1997

Risk factors for recurrence of hemorrhagic endovasculitis of the placenta.

OBJECTIVE: To assess the potential for recurrence of placental hemorrhagic endovasculitis and to identify clinical or pathologic cofactors that might influence recurrence of this lesion or subsequent pregnancy outcome. METHODS: Ninety-seven women with a placenta affected by hemorrhagic endovasculitis, who also had at least one placenta referred to the Michigan Placental Tissue Registry from a subsequent pregnancy, were identified from 10,531 referrals between 1978 and 1988. Histologic slides from 209 placentas and clinical data from 211 infants (two sets of twins) from initial (first) and subsequent referrals were analyzed. Placentas were graded for the presence, extent, and severity of hemorrhagic endovasculitis and chronic villitis of unknown etiology; for placental lesions indicative of hypertensive maternal vessel disease; and for intravascular nucleated erythrocytes and chorionic thrombi. Maternal data included age, gravidity, number of previous losses, and history of toxemia or hypertension. All data were analyzed for significance using chi2 and t tests. Outcome assessment was based on recurrence of hemorrhagic endovasculitis and infant viability with the second referral. RESULTS: With first referrals, 80 of 98 infants (81.6%) were stillborn. Among second referrals, 26 of 98 infants (26.5%) were stillborn. Hemorrhagic endovasculitis recurred in 28 second placentas (28.9%); of these, 18 infants (64.3%) were stillborn. Higher rates of recurrence were found with progressively higher first-referral chronic villitis severity scores (P < .02), higher hypertensive placental lesion scores (P < .001), and first referrals with a history of toxemia or hypertension (P < .02). Recurrence of hemorrhagic endovasculitis was higher in patients with two or more of these factors in first referrals (P < .001). Subsequent stillbirth was more frequent with progressively higher first-referral hypertensive placental lesion scores (P < .01) and in first placentas with two or more risk factors (P = .064). Hemorrhagic endovasculitis severity scores, intravascular nucleated erythrocytes, and chorionic thrombi were associated with stillbirth in index pregnancies only. Maternal age, gravidity, or history of prior losses were not predictive. CONCLUSIONS: Placental hemorrhagic endovasculitis is associated with pregnancy loss and can recur in some patients. Interrelations among placental hemorrhagic endovasculitis, chronic villitis, maternal hypertension, and adverse outcomes in subsequent pregnancies are apparent. This information may be useful in patient counseling.

Adolescent↗
PubMed1999

Telomerase and proliferative activity in placenta from women with and without fetal growth restriction.

OBJECTIVE: To analyze telomerase and proliferative activity in placenta from women with and without fetal growth restriction (FGR). METHODS: Telomerase activity was analyzed in 30 first-trimester chorionic villi specimens (group A) and in 28 second- and third-trimester placenta specimens (group B) from women without FGR. Telomerase activity also was analyzed in 11 placenta specimens from women with asymmetric FGR (group C). The proliferative activity of these 69 specimens was assessed by immunohistochemical staining, using the MIB-1 monoclonal antibody. RESULTS: Telomerase activity was detected in 28 (93.3%) of 30 chorionic villi specimens and in 18 (64.3%) of 28 placenta specimens without FGR. In contrast, no telomerase activity was exhibited in the placenta specimens from any of the 11 women with asymmetric FGR by telomeric repeat amplification protocol assay. Telomerase activity also was detected by in situ telomeric repeat amplification protocol assay in trophoblastic cells from women without FGR but not in trophoblastic cells from women with asymmetric FGR. Thus, telomerase activity was detected significantly more often in groups A and B than in group C (P < .01). The rate of proliferative activity, evident as positive MIB-1 staining in trophoblastic cells, in groups A and B (28.1+/-1.7% and 7.0 +/-2.9%, respectively) was significantly higher than that in group C (1.9+/-0.6%; P < .01). CONCLUSION: Telomerase and proliferative activity were minimal in placenta from women with asymmetrical FGR, suggesting placental senescence with asymmetrical FGR.

Cell Division↗
PubMed1998

Twins, placentas, and genetics: acardiac twinning in a dichorionic, diamniotic, monozygotic twin gestation.

We describe a human acardiac twin with associated vascular anastomoses in a dichorionic diamniotic fused twin placenta. A 22-year-old woman delivered a healthy 3,554 g male infant and a fused diamniotic dichorionic twin placenta with a 230 g umbilical cord-attached, skin-covered, ovoid mass, consistent with acardiac amorphus. By gross and histological examination, the placental dividing membranes comprised four leaves, one amnion from each placenta, and two centrally fused chorions, diagnostic of dichorionicity. Placental barium injection of the normal twin's umbilical vein showed an anastomosis with the acardiac twin which traversed the dividing membranes, then supplied major vessels of the acardiac mass via its 5.5 cm umbilical cord. DNA-typing studies of the normal twin's placenta and of the acardiac twin's tissues revealed identical alleles at 11 distinct genetic polymorphic loci, consistent with monozygosity. Our findings demonstrate that vascular anastomoses can occur in dichorionic twin placentas, and that human acardiac twinning is not, as heretofore believed, restricted to monochorionic placentas.

Abnormalities, Severe Teratoid↗
PubMedDate not supplied

Placentae of light for dates infants born to underweight mothers at term: a morphometric study.

Fifteen light for dates infants and their placentae were compared to 15 well-grown infants and their placentae. The former were born to thin, underweight women while the latter were born to women of normal weight. The light for dates infants were symmetrically growth retarded but not wasted at delivery and their placentae had a reduced weight, volume, chorionic surface area, percentage parenchyma and total villous surface area. The peripheral villous surface area and volume of peripheral villous trophoblast, fetal capillaries and connective tissue was also reduced in the placentae of light for dates infants, suggesting retarded placental growth in the latter half pregnancy. In contrast, the stem villous surface area and volume of stem villous trophoblast, fetal capillaries and connective tissue was similar in both groups of placentae, suggesting the same rate of growth in early pregnancy. There were no differences in the volume of fibrin or infarcts. The ratio of total villous surface area to infant weight, length and head circumference was reduced in the light for dates infants. This may restrict the materno-fetal oxygen exchange, and thereby increase the risk of fetal hypoxia during labour. It is concluded that the placentae of light for dates infants born at term to underweight women are both absolutely and relatively small with a reduced villous surface area.

Adult↗