Ultrastructure of the epithelium of the chorionic villi of the human placenta

Demir, Ramazan

doi:10.1159/000145165

Cited by 12 publications

(3 citation statements)

References 8 publications

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“…Semithin sections (thickness, 0.5 m) were stained with toluidine blue. Ultrathin sections (thickness, 70 nm) were double-stained with uranyl acetate and lead citrate [16,17].…”

Section: Electron Microscopymentioning

confidence: 99%

Apoptosis Contributes to Vascular Lumen Formation and Vascular Branching in Human Placental Vasculogenesis1

Tertemiz

Kayisli

Arıcı

et al. 2005

Biology of Reproduction

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Placental vasculogenesis consists of several stages, including appearance of hemangioblasts and angiogenic cell islands, setting up a primitive vascular network, and transition from vasculogenesis to sprouting and nonsprouting angiogenesis. In the present study, we hypothesized that placental vasculogenesis and angiogenesis require apoptosis during the formation of primitive vascular pattern, vessel elongation, and angiogenic branching. Vasculogenesis and apoptotic cells were identified using CD31 immunohistochemistry, hematoxylin-eosin (H-E) staining, CD31-TUNEL double-labeling, and transmission-electron microscopy (TEM). No TUNEL-positive cell was detected in angiogenic cell islands; however, several TUNEL-positive cells were observed during the primitive lumen formation. Interestingly, some of the stromal cells located between vasculogenic areas during the endothelial tube elongation and angiogenic branching also were TUNEL-positive. The presence of morphological aspects of apoptosis, such as nuclear shrinkage and nuclear bodies (apoptotic bodies), also was confirmed in H-E-stained and TEM-depicted sections. Quantitative analysis showed that higher ratios for apoptotic cells were found in the core stroma of villi among the vascular branching areas and in the primitive capillary lumen compared to angiogenic cell cords and vasculatures with advanced lumens (P < 0.05). In conclusion, our results suggest that apoptosis likely is involved in the physiologic mechanisms of placental vasculogenesis and angiogenesis, such as lumen formation and angiogenic branching.

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“…Semithin sections (thickness, 0.5 m) were stained with toluidine blue. Ultrathin sections (thickness, 70 nm) were double-stained with uranyl acetate and lead citrate [16,17].…”

Section: Electron Microscopymentioning

confidence: 99%

Apoptosis Contributes to Vascular Lumen Formation and Vascular Branching in Human Placental Vasculogenesis1

Tertemiz

Kayisli

Arıcı

et al. 2005

Biology of Reproduction

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“…According to alteration of protein synthesis for VEGF and its receptors, it is possible to be the slight functional changes of the placental components. In the cases of full term human placental barrier, a more severe structural complication characterized by evident ultrastructural alterations (Demir 1979(Demir , 1980, only some placental components might be able to make a function like-nefro-pneumoid units for transportation and secretion of some substances (Demir et al1995).…”

Section: Discussionmentioning

confidence: 99%

“…Samples of human placental tissues were fixed by immersion in 2.5% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4) at room temperature for 4 h and post-fixed in 1% phosphate-buffered osmium tetroxide for 2 h (Demir, 1980). The specimens were dehydrated in ascending concentrations of ethanol and embedded in Araldite-epoxy resin.…”

Section: Methodsmentioning

confidence: 99%

Expression of VEGF receptors VEFGR-1 and VEGFR-2, angiopoietin receptors Tie-1 and Tie-2 in chorionic villi tree during early pregnancy.

Demir

2010

Folia Histochem Cytobiol.

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Abstract:The aim of this study was to determine the expression of VEGF and its receptors in placentas from normal pregnancies between 22 days p.c. and 48 days p.c. of very early pregnancy. Placental tissues carried out from 19 pregnant women were examined. Immunohistochemical technique, electron microscopy were employed to evaluate the factors expression. In the new developing mesenchymal villi and immature intermediate villi VEGF and its receptors VEGFR-1 and VEGFR-2 immunoreactivity was detected in all the placental components, while in the stem villi and in the chorionic plate with large vessels only in some components. In the mesenchymal villi and immature intermediate villi VEGFR-1 and -2, and angiopoietin receptors Tie-1 and -2 immunoreactivity was dominantly observed in the heamangiogenic cells and cells cords, whereas the matured villi showed immunoreactivity only in other components. The ultrastructural findings were higher in respect to the all of the early pregnancy days. The placental samples from all of pregnancies, showed the VEGF and its receptors in optimal expression levels, whereas the angiopoietin receptors Tie-1 and -2 showed a higher expression levels in respect to other study factors. The receptors protein levels increased from the early days to the advanced days of gestation, but this alteration was not significant. The intensity of the immunolabeling for these proteins were not significant compared to to each other of gestatin days were examined. These findings demonstrated that a dysregulation of the placental expression of the VEGF and its receptors related to the different degrees of the gestational periods. Probably, this event may be related to complete vasculugenesis and angiogenesis in placental villi.

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Fetal membranes and placenta of the african green monkey (Cercopithecus aethiops)

1989

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This study examined developmental changes in fetal membranes and placenta of Cercopithecus aethiops from a Carnegie developmental stage 12 embryo to near-term fetuses. Ultrastructurally, yolk sac cells (endoderm and mesothelium) were similar to comparable stages in other primates. Endodermal cells had few apical microvilli, abundant rough-endoplasmic reticulum, electron dense mitochondria and dense bodies. In contrast, mesothelial cells were squamous with numerous microvilli, small mitochondria and a few short strands of rough endoplasmic reticulum. Amnion cells early in gestation were squamous with few microvilli, large glycogen deposits and poorly developed cytoplasmic components. Tight junctions and desmosomes held adjacent cells together. The basal surface was smooth and the basal lamina was distinct. As development proceeded the amniotic cells became cuboidal and possessed numerous microvilli. Cytoplasmic organelles were better developed and glycogen deposits increased by mid-gestation. A thick layer of microfibrils and collagen fibers was prominent below the basal lamina. Near-term, the glycogen had virtually disappeared and the amount of lipid droplets increased. Basal infoldings and podocytic processes and the extracellular matrix had increased. The smooth chorion consisted of pseudostratified columnar cells. Cells had short microvilli, numerous granules and vesicles of variable size and electron density in early gestation. With increasing age, amounts of granules and vesicles decreased, as the endoplasmic reticulum became prominent. The chorionic trophoblast was a continuous layer in mid-pregnancy and its cells had well-developed organelles and inclusions. Late in gestation, the trophoblastic layer became discontinuous and wide intercellular spaces and channels were present. In the placenta, the trophoblastic elements showed features characteristic of primate placenta.

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Ultrastructure of the epithelium of the chorionic villi of the human placenta

Cited by 12 publications

References 8 publications

Apoptosis Contributes to Vascular Lumen Formation and Vascular Branching in Human Placental Vasculogenesis1

Apoptosis Contributes to Vascular Lumen Formation and Vascular Branching in Human Placental Vasculogenesis1

Expression of VEGF receptors VEFGR-1 and VEGFR-2, angiopoietin receptors Tie-1 and Tie-2 in chorionic villi tree during early pregnancy.

Fetal membranes and placenta of the african green monkey (Cercopithecus aethiops)

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