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PubMed1995

Using the number of yolk sacs to determine amnionicity in early first trimester monochorionic twins.

The purpose of this study was to evaluate the relationship between the number of yolk sacs and amnionicity in monochorionic twin pregnancies scanned early in the first trimester. We retrospectively reviewed images of all monochorionic twins scanned between 6 and 9.5 weeks' gestation and with pathologic or sonographic confirmation of chorionicity-amnionicity. Each film was reviewed for the number of yolk sacs present, as well as for the gestational age at which the amniotic membrane was first visualized. Twenty monochorionic-diamniotic pregnancies and two monochorionic-monoamniotic pregnancies met the criteria for inclusion in the study. In diamniotic pregnancies scanned at less than 8 weeks' gestation, only the yolk sacs were identified; none of the dividing amniotic membranes were detected. Two yolk sacs were identified in all but one case. In this case, although one yolk sac was seen at 6 weeks, follow-up scanning at 8 weeks revealed two yolk sacs. In each of the monochorionic-monoamniotic twin pregnancies, one yolk sac was seen at 9 weeks and a single amnion encircled both embryos. We conclude that the sonographic identification of two yolk scas in monochorionic twins enables us to make the diagnosis of diamniotic twins early in the first trimester, before the amniotic membrane can be imaged. The presence of one yolk sac should prompt a follow-up ultrasonogram to assign amnionicity definitively.

Adult↗
PubMed2004

Reconstructive surgery of male urethra using human amnion membranes (grafts)--first announcement.

OBJECTIVE: Assessment of technical aspects of the surgical procedure and usefulness, suitability and efficacy of human amnion grafts as a biomaterial in reconstructive surgery of strictured male urethra. PATIENTS AND METHODS: Human amnion membranes were used in 2 men suffering from long, recurring strictures of urethra. Narrowed part of urethra was careful prepared and cleaned of adjacent tissue. Then a longitudinal incision was performed through the whole length of strictured segment and then it was covered with human amnion membrane. RESULTS: Hospitalization time 4 to 5 days. The Foley catheter was removed 2 weeks after surgery 3 months after surgery controlled urethrographies and urethroscopies show wide urethra lumen, wider than in adjacent parts. In urethroscopy operated place covered with epithelium, smooth, without scare. CONCLUSIONS: Human amnion grafts and described technique seem to be a promising method of managing long, recurring male urethra strictures but need long-term follow-up and analysis of more cases.

Amnion↗
PubMed2006

[A comparative study on acellular small intestinal submucosa and acellular amnion as dressings for traumatic skin defects].

OBJECTIVE: To compare the reparative effects between the acellular small intestinal submucosa and the acellular amnion as dressings for traumatic skin defects. METHODS: Three full-thickness skin defects, which were close to the vertebral column of the pig, were created on both sides of the dorsum. The skin defects were randomly divided into three groups. In each group, the following different materials were used to cover the skin defects: the acellular amnion in Group A, the acellular small intestinal submucosa (SIS) in Group B, and the physiological saline gauze in Group C (the control group). The specimens from the skin defects were harvested for a histological evaluation and for determination of the hydroxyproline content at 10 (2 pigs), 20 (2 pigs), and 30 days (3 pigs). We observed the healing process of the wound and its healing rate, counted the inflammatory cells, vascular endothelial cells, and proliferating cells, and determined the hydroxyproline content. RESULTS: The acellular amnion in Group A and the acellular SIS in Group B adhered to the wound tightly, but they did not adhere to the dressing; when the dressing was changed, the wound did not bleed. The saline gauze in Group C adhered to the wound tightly, but when the dressing was changed, the wound bled until 22 days after operation. Under the microscope, the collagen in the tissue below the epithelium was arranged more regularly and there were fewer cells concerned with inflammation in Groups A and B than in Group C at 10, 20, and 30 days after operation. At 10, 20, and 30 days after operation, the wound healing rate was greater in Groups A and B than in Group C. The number of the inflammatory cells and the proliferating cells were greater in Group C than in Groups A and B. There was a statistically significant difference (P < 0.05), At 20 and 30 days after operation, the content of hydroxyproline was greater in Group C than in Group A and B. There was a statistically significant difference (P < 0.05). However, there was no statistically significant difference between Group A and Group B in the wound healing rate, the numbers of the inflammatory cells, vascular endothelial cells and proliferating cells, and the content of hydroxyproline (P > 0.05). There was no statistically significant difference among the three groups in the number of the vascular endothelial cells. CONCLUSION: Compared with Group C, the wound healing rate is improved, the collagen in the tissue below the epithelium is arranged more regularly, and the inflammatory cells, bleeding, and effusion are reduced in Groups A and B. The reparative effects of the acellular amnion and the acellular small intestinal submucosa as dressings on the skin defects are almost the same.

Amnion↗
PubMedDate not supplied

[The effect of temperature on the motor activity of the chick embryo and amnion at 5-14 days of development].

It has been shown that cooling the developing eggs from 37.7 degrees C results cessation of motor activity of the amnion in 5-14-day embryos at 36-33 degrees C, whereas motor activity of the embryo remains unaffected up to 31-26 degrees C. Immobilization of the embryo was observed on cooling up to 22-18 degrees C. The recovery of motor activity after cooling during heating takes place in a reverse order. Embryonic movements are observed at 18-23 degrees C, contractions of the amnion--at 28-33 degrees C. These experiments reveal complete independence of embryonic movements from the amnion. Motor activity of the amnion is related to that of the embryo only between the 8th and the 10th day of incubation.

Amnion↗
PubMed1986

Interferon-gamma induces class I HLA and beta 2-microglobulin expression by human amnion cells.

In contrast to other human nucleated cells, amnionic epithelial cells do not normally express class I HLA antigens. It is not known whether the failure of display of those antigens occurs because genes for HLA expression are deleted or are defective, or if gene expression is repressed. The results of the present study demonstrate that amnionic epithelial cells exposed to IFN-gamma express levels of class I HLA antigens and beta 2-microglobulin that are readily detectable in immunoperoxidase and immunofluorescence stains. The findings suggest that failure of transcription may be responsible for failure of normal expression of class I HLA antigens and beta 2-microglobulin by cells of the amnion membrane. Class II antigens, which are normally expressed by very few cell types, were not expressed by amnion cells under any test conditions.

Amnion↗
PubMed1988

Endotoxin stimulates prostaglandin E2 production by human amnion.

The studies presented in this report were designed to evaluate whether bacterial endotoxin alters the rate of biosynthesis of prostaglandin E2 (PGE2) by human amnion. Amnion cells were established in primary monolayer culture from women undergoing elective cesarean sections. Endotoxin from Escherichia coli and Salmonella typhosa were incubated with amnion cells for 16 hours, and radioimmunoassay was used to measure PGE2 released into the media. Bacterial endotoxin demonstrated a concentration-dependent stimulatory effect on the rate of PGE2 synthesis by amnion cells. These observations suggest a mechanism for the onset of labor associated with intra-amniotic infection.

Amnion↗
PubMed1986

Monoclonal antibodies to human amnion recognize different components of the rabbit eye.

The epithelium of the eye originates from embryonic ectoderm, whereas the amnion is an extra-embryonic membrane that bears close relationship with many ectodermal tissues. Shared antigens have been identified between human amnion and cornea using rabbit antisera to human amnion. Three monoclonal antibodies to human amnion, GB4, GB9, and GB11 were studied by immunofluorescence on the anterior segment of the rabbit eye. GB4 recognized the epithelium of the conjunctiva and the subcapsular epithelium of the lens. GB9 reacted only with the central four fifths of the corneal epithelium; the peripheral epithelium near the limbus was not reactive. GB11 detected the pigmented epithelial cells in ciliary processes.

Amnion↗
PubMed1983

Permeability of ovine amnion and amniochorion to urea and water.

Permeability of ovine amnion and amniochorion to urea and water was measured in vitro at various gestational ages. Permeability of amniochorion was between 30 and 100% of that of amnion. Permeability of the membranes to water did not change with fetal age, whereas permeability of amnion to urea decreased from 1.548 +/- 0.541 (49) 10(-4) cm . sec-1 to 0.277 +/- 0.339 (102) 10(-4) cm . sec-1 as fetal age increased. There was a significant relationship between the permeability of the amnion to urea and the concentration of urea in the amniotic fluid. It was concluded that the decrease in membrane permeability to urea may be responsible in part for the increase in amniotic fluid urea concentration observed as gestation progresses.

Amnion↗
PubMed1982

[Light- and electron microscope studies of human fetal membranes. 1. Amnion and intermediate layer].

In the course of a series of histiophysiological tests, a structural analysis was made of the different layers of foetal membranes. They were based on optical light and electron microscopy. Particular attention was given to the question for the secretory and resorptive faculties of this intermediate layer between the compartments of mother and amniotic fluid. --The first tests were made by means of amnion morphology, histochemistry, and thin-layer chromatography for the purpose of elucidating the composition of lipid droplets. Their form and chemical composition were both found to be similar to those of lipid droplets (liposomes) which were suspended in amniotic fluid. This fact, together with the morphological aspect, was likely to indicate hat the liposomes were expelled by exocytosis from amniotic epithelial cells. The endoplasmatic reticulum was active and granular, an indicator to sizeable formation of proteins in the amniotic epithelial cells. --Analysis by thin-layers chromatography showed lipids in both the amnion and amniotic fluid to consist of lysolecithin, sphingomyelin, phosphatidylserin, phosphatidylinosite, lecithin, kephalin, phosphatidyl-ethanolamine, cholesterinester, triglycerides, and sebacic acids. --The large intercellular spaces in the amniotic epithelium were found to form a labyrinth between surface differentiations of surrounding cell walls. There were numerous vesicles in the amniotic epithelial cells which were attributed to absorption of amniotic fluid from intercellular spaces as well as to its emission to cell surfaces. Some of the amniotic fluid was removed through the connective tissue of the amnion. Fibroblasts, located in connective tissue of the amnion, differed from connective tissue cells of adults, in that they were highly capable of synthesizing and storing both lipids and glycogen. They were also capable of meconium storage. Structures recorded by electron microscopy from the intermediate layer were safely identified as remnants of extraembryonic mesenchyma.

Amnion↗
PubMed1980

[Formation of amnion cord in a young defective human embryo (author's transl)].

A report about a human embryo of about 4 weeks of age afflicted with the formation of amnion cord with a slinglike formation. The corion sac had on its surface only a sparse cover with chorion vili. The intraembryonical vascular system was not shown except of small partial spaces in the front sector. The cause for the formation of an amnion cord is seen primarily in a faulty supply of the amniotic sac with its content. The formation of an amnion cord has been interpreted for this early phase of the embryogenesis as follows: In sufficiency of nourishment led to a dehiscence of the amnion. Mesenchym entered from the extraembryonal celom and combined itself with the lateral wall of embryo which showed because of insufficient nourishment in one area of defective epithelium. The mesenchym, which surrounded the frontal trunk part did not connect with the embryo and grew because of growth pressure into a loop with collagenous fibers. Amnionepithelecells spread only secondarily over the mesenchymloop and epithelialized it.

Abortion, Spontaneous↗
PubMed1981

Glycosaminoglycans and collagen in human amnion from pregnancies with and without premature rupture of the membranes.

Glycosaminoglycans and collagen were measured in dried samples of human amnion from pregnancies with and without premature rupture of the membranes. The major sulphated glycosaminoglycans were dermatan and chondroitin sulphates. The concentration of sulphated glycosaminoglycans decreased significantly towards term in both groups of patients (with, r=--0.720, and without, r=-0.631, premature rupture of membranes), the decrease occurring earlier in gestation in the PROM group (P less than 0.005). There was a positive correlation between the sulphated glycosaminoglycan and collagen concentrations in both groups of samples (with, r = 0.697 and without, r = 0.493, premature rupture of membranes). The only unsulphated glycosaminoglycan identified in amnion was hyaluronate which was present in higher concentrations (P less than 0.005) in term samples (10.67 +/- 5.5 microgram/mg) than in pre-term samples (5.45 +/- 2.98 microgram/mg). There was a negative correlation between the hyaluronate and collagen concentrations (r = -0.455). The associations between decreasing concentration of both sulphated glycosaminoglycan and collagen with increasing concentrations of hyaluronate in amnion are consistent with observed changes in the tensile properties of the amnion towards term and are explicable in terms of accepted mechanisms of connective tissue remodelling.

Amnion↗
PubMed1977

Human amnion metabolism. II. Incorporation of fatty acids into tissue phospholipids in vitro.

The rate of incorporation of 3H-arachidonic acid and 14C-palmitic acid into 15 term amniotic membranes was studied during incubation of tissues in an artificial amniotic fluid medium. Phospholipids were extracted from the amnions, separated by thin-layer chromatography, and both the radioactivity and the phosphorus associated with each phospholipid species were determined. The distribution of amnion phospholipids was: lecithin, 47 per cent; phosphatidyl ethanolamine, 30 per cent; sphingomyelin, 7 per cent; phosphatidyl inositol, 5 per cent; lysolecithin, 4 per cent; and other phospholipids, 6 per cent. During incubation, the specific activities of the phospholipids became maximal after 2 hours and remained constant for at least the next 2 hours. Arachidonic acid was incorporated mainly into lecithin (53 per cent) and phosphatidyl ethanolamine (27 per cent) whereas palmitic acid was incorporated mainly into lecithin (70 per cent). Incorporation of fatty acids was 33 per cent higher in amnions obtained after vaginal delivery than in those obtained before labor. From the known fatty acid composition of amnion phospholipids, it is concluded that there is a high rate of turnover of arachidonic acid relative to palmitic acid in lecithin.

Amnion↗
PubMed1993

The effects of vanadate and epidermal growth factor on the specific activities of phospholipase A2 and phosphatidylinositol-specific phospholipase C in human amnion cells.

We have evaluated the specific activity of phospholipase A2 (PLA2) and phosphatidylinositol-specific phospholipase C (PLC) in human amnion cells in monolayer culture that had not (CTL) or that had been treated with vanadate (VAN) and/or mouse epidermal growth factor (mEGF) for 4 h. It is known that both agents stimulate prostaglandin (PG) E2 synthesis in these cells. Phospholipase enzyme activities were determined in the 750 x g supernatant fraction of amnion cell homogenates under optimal in vitro conditions. The specific activity of PLA2 ranged from 1.1 to 1.25 nmol/mg protein/0.5 h and that of phosphatidylinositol-specific PLC from 1.04 to 1.2 mumol/mg protein/h. Treatment of amnion cell cultures with VAN and/or mEGF had no statistically significant effect on the specific activities of either phospholipases. Thus, we conclude that the stimulation of PGE2 production by VAN and mEGF is not due to an increase in the release of arachidonic acid from glycerophospholipid storage forms in human amnion cells.

Amnion↗
PubMed1996

Analogs of cord red blood cell membrane components displayed on placenta, amnion and amniotic cells in culture.

Placenta and amnion were analyzed to ascertain the presence of antigens in common with red blood cells (RBC) from cord or fetuses. The expression of distinct antigens displayed on a subpopulation of cord RBC and detected by anticord RBC membrane antibodies was particularly investigated, concomitantly with the presence of transferrin receptors (TR) by employing immunohistochemistry. The placenta showed both cord antigen and TR; on the contrary, amnion--which was labelled by anti-cord RBC membrane antibodies--was not stained by the anti-TR antibody. The results of inhibition and double labelling assays further excluded TR as the relevant antigen in the labelling of both placenta and amnion. The staining of fetal membranes disappeared after absorption of antibodies with cord RBC membranes. These results suggest that the antigens externally expressed on a subpopulation of cord RBC are shared by amnion and placenta.

Amnion↗
PubMedDate not supplied

Changes in blood flow to the ovine chorion and amnion across gestation.

OBJECTIVE: The purpose of this study was to determine the developmental changes in blood flow to the network of fetal microvessels in ovine chorion and amnion. METHODS: Colored microspheres (15.10 +/- 0.02 [standard deviation] mu in diameter) were infused into the superior vena cava in nine chronically catheterized fetal sheep with gestational ages ranging from 103-141 days (term 147). After euthanasia, chorion, amnion, and cotyledons were separated and microspheres were counted to determine blood flow rates. Standard correlation and regression analyses were used to analyze the data. RESULTS: Chorionic blood flow rate increased linearly (r = 0.82, P = .006) from 12 mL/minute at 103 days' gestation to 70 mL/minute at 141 days, and averaged 10.3 +/- 1.2% of the total umbilical blood flow. Weight-normalized chorionic flow (18.4 +/- 2.0 [standard error] mL/minute/kg of fetus) did not change significantly across gestation. Absolute and weight-normalized blood flow to the amnion (0.82 +/- 0.31 mL/minute and 0.34 +/- 0.11 mL/minute/kg fetus) increased with advancing gestation until 130 days and declined thereafter. Absolute cotyledonary blood flow rate increased with gestational age (r = 0.81, P = .008), and weight-normalized cotyledonary blood flow decreased with advancing gestation (r = -0.89, P = .002). Absolute but not weight-normalized chorionic and cotyledonary blood flow rates correlated positively. CONCLUSIONS: Blood flow to the microvascular network in the ovine chorion is high and increases with advancing gestation. Blood flow to the amnion is low but not insignificant. Therefore, intramembranous exchange may play an increasingly important role in determining amniotic fluid volume and composition as gestation proceeds.

Amnion↗
PubMed1998

Sonographic assessment of chorionicity and amnionicity in twin pregnancies: how, when and why?

During the first trimester, chorionicity can be assessed as early as five weeks post-conception, but a reliable detection of amnionicity cannot be performed before the 8th week when the amnion can be clearly imaged. The late second and third trimesters twin pregnancies are a true challenge to the imaging specialist because the detection of chorionicity and amnionicity has to rely upon sonographic clues, such as placenta location, fetal gender, membrane origin, thickness, and layer. Sonographic methods used to determine chorionicity and amnionicity in twins can be extrapolated to any multifetal pregnancy, regardless of the number of fetuses present.

Amnion↗
PubMed1976

Fetal respiration: quantitative measurements of amnionic fluid inspired near term by human and rhesus fetuses.

Observations reported now on primate pregnancies, human and rhesus, combined with earlier studies from this laboratory, demonstrate that normally appreciable volumes of amnionic fluid are inhaled and presumably exhaled throughout much of pregnancy. Through use of isotope-labeled red cells and porcelain microspheres placed at varying times in the amnionic sac, as well as fetal squames already present, it has been shown conclusively that inhalation of amnionic fluid is not necessarily a pathologic event. The volumes of amnionic fluid inhaled per 24 hours by human and rhesus fetuses late in pregnancy were remarkably similar, amounting on the average to at least 200 ml per kilogram. These observations confirm the much earlier qualitative studies of some others that previously had generally been discounted by many fetal physiologists.

Amniotic Fluid↗
PubMed1996

Clinical amnionitis and endometritis in patients with premature rupture of membranes: endocervical prostaglandin E2 gel versus oxytocin for induction of labor.

OBJECTIVE: To compare the rates of clinical amnionitis and endometritis in patients with premature rupture of membranes (PROM), using endocervical prostaglandin E2 (PGE2) gel for induction of labor versus immediate oxytocin induction of labor. METHODS: We randomized 118 patients to receive either endocervical 0.5 mg of PGE2 gel (study group) or immediate oxytocin induction of labor (control group). If labor was not established in the group receiving PGE2 gel in 24 hours, intravenous oxytocin was given in incremental doses. The rates of clinical amnionitis and endometritis in the two groups were analyzed. Also compared were hours of labor, duration of rupture of membranes and number of vaginal examinations. Student t test, chi 2, or Wilcoxon rank-sum test were used for statistical analysis, as appropriate. P < .05 was considered significant. RESULTS: The rates of clinical amnionitis were 5.3% in the PGE2 group and 8% in the control group. Endometritis developed in 1.7% of PGE2 patients and 3.2% of controls. These differences in maternal infection rates were not statistically significant. The two groups were comparable with respect to age, parity, and antepartum group B streptococcal colonization. No significant differences in hours of labor, duration of ruptured membranes, or vaginal examinations were observed. Neonatal outcome data (mean birth weight, Apgar scores at 1 and 5 minutes, Apgar score less than 7 at 5 minutes) were not statistically significant. CONCLUSION: Endocervical placement of 0.5 mg of PGE2 gel does not increase the incidence of clinical amnionitis and endometritis in patients with PROM at term when compared with immediate induction of labor with oxytocin.

Administration, Topical↗