The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Marios Loukas - One of the best experts on this subject based on the ideXlab platform.
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human spinal arachnoid Villi revisited immunohistological study and review of the literature
Journal of Neurosurgery, 2007Co-Authors: Shane R Tubbs, Ake Hansasuta, William R Stetler, David R Kelly, Danitra Blevins, Rita Humphrey, Gina D Chua, Mohammadali Mohajel Shoja, Marios LoukasAbstract:Object Few have described the relationship between arachnoid protrusions (Villi) and adjacent spinal radicular veins, and the descriptions that do exist are conflicting. Some authors have even denied the presence of spinal arachnoid Villi, suggesting that they play no role in cerebrospinal fluid (CSF) absorption. Methods To further elucidate these structures, laminectomies from C-2 inferiorly to S-2 were performed in 10 fresh human adult cadavers. Following removal of the laminae, the dural nerve sleeves were identified and the spinal nerves excised 1 cm lateral and medial to the intervertebral foramina. Samples were submitted for histological and immunohistological analysis. Results The authors identified arachnoid Villi in all specimens. The length of these structures was approximately 50 to 170 μm. Regionally, these Villi were more concentrated in the lumbar region, but they were not present at every vertebral level, with observed skip zones. Occasionally, more than one villus was identified per verteb...
Barry F. King - One of the best experts on this subject based on the ideXlab platform.
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Scanning electron microscopy of primate chorionic Villi following ultrasonic microdissection
Placenta, 1991Co-Authors: Barry F. KingAbstract:Abstract Villi from human, macaque and baboon placentae were subjected to ultrasonication after prolonged osmication, and examined by scanning electron microscopy. The technique was often successful in removing the overlying trophoblast and revealing expanses ofthe trophoblastic basal lamina, a conclusion corroborated by transmission electron microscopy. These preparations bore a remarkable similarity in appearance to microvascular cast preparations of the fetal vasculature. Relatively straight parallel tubules appeared to correspond in position to the location of fetal vessels in intermediate Villi, whereas portions of the basal laminae of terminal Villi were in the form of convoluted, branched cylinders similar to SEM images offetal capillaries of terminal Villi. The basal lamina did not have evidence ofpores as has been described in some basal laminae.
D M Nelson - One of the best experts on this subject based on the ideXlab platform.
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apoptotic changes occur in syncytiotrophoblast of human placental Villi where fibrin type fibrinoid is deposited at discontinuities in the villous trophoblast
Placenta, 1996Co-Authors: D M NelsonAbstract:The syncytial nature and surface location of the trophoblast layer of human placental Villi positions the syncytiotrophoblast to regulate maternal-fetal exchange of molecules while also providing a barrier function. However, discontinuities in the syncytiotrophoblast breach the integrity of this interface, and deposition of fibrin type fibrinoid on the trophoblast basal lamina at the syncytial discontinuity provides a matrix for trophoblast re-epithelialization. Using the electron microscope, I tested the hypothesis that apoptosis in the syncytiotrophoblast was one process that initiated discontinuity in the trophoblast layer of term placental Villi. Ultrastructural analysis of fibrin deposits on Villi from six placentae from uncomplicated term pregnancies indicated the following morphological features typical of apoptosis: condensation and margination of chromatin along an intact nuclear envelop in syncytiotrophoblast nuclei associated with villous surface fibrin deposits; loss of microVilli with membrane blebbing on the surface membrane; cytoplasmic condensation; autophagocytosis of cellular debris containing nuclear fragments; absent inflammatory response. I conclude that human placental syncytiotrophoblast undergoes apoptosis, and this process is associated with breaks in the trophoblast covering of Villi. The presence of trophoblastic apoptosis, and of discontinuities in the trophoblast layer of term Villi, provide new insights into the pathways for maternal-fetal exchange in the human placenta.
V Krejci - One of the best experts on this subject based on the ideXlab platform.
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the branching pattern of villous capillaries and structural changes of placental terminal Villi in type 1 diabetes mellitus
Placenta, 2012Co-Authors: Marie Jirkovska, Tomas Kucera, J Kalab, M Jadrnicek, V Niedobova, Jiři Janacek, Lucie Kubinova, M Moravcova, Zdeněk žižka, V KrejciAbstract:Maternal diabetes is associated with changes of the placental structure. These changes include great variability of vascularity manifested by strikingly hypovascular as well as hypervascular terminal Villi. In this paper, normal placental terminal Villi and pathological Villi of type 1 diabetic placentas were compared concerning the structure of villous stroma, spatial arrangement of villous capillary bed and quantitative assessment of capillary branching pattern. Formalin fixed and paraffin embedded specimens of 14 normal and 17 Type 1 diabetic term placentas were used for picrosirius staining, vimentin and desmin immunohistochemistry and confocal microscopy. 3D models of Villi and villous capillaries were constructed from stacks of confocal optical sections. Hypervascular as well as hypovascular Villi of diabetic placenta displayed changed structure of villous stroma, i.e. the collagen envelope around capillaries looked thinner and the network of collagen fibers seemed less dense. The desmin immunocytochemistry has shown that stromal cells of hypervascular as well as hypovascular Villi appeared nearly or completely void of desmin filaments. In comparison with normal Villi, capillaries of hypovascular Villi had a smaller diameter and displayed a markedly wavy course whereas in hypervascular Villi numerous capillaries occurred in reduced stroma and often had a large diameter. The quantitative assessment of capillary branching has shown that villous capillaries are more branched in diabetic placentas. It is concluded that type 1 maternal diabetes enhances the surface area of the capillary wall by elongation, enlargement of diameter and higher branching of villous capillaries and disrupts the stromal structure of terminal Villi.
R. J. H. Galjaard - One of the best experts on this subject based on the ideXlab platform.
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potential false negative diagnoses in chorionic Villi and a review of the literature
Prenatal Diagnosis, 2006Co-Authors: Cardi Van Den Berg, Diane Van Opstal, Joke Polakknook, R. J. H. GaljaardAbstract:Objectives To assess the incidence of (potential) false-negative findings of cytogenetic diagnosis in STC-Villi and/or LTC-Villi and to determine the best strategy for karyotyping chorionic Villi in order to avoid false-negative results. Methods 2476 chorionic villus samples were received for prenatal cytogenetic investigations. Karyotyping was routinely performed on STC- and LTC-Villi preparations by G-banding. Fluorescence in situ hybridization (FISH) analyses were performed in addition to standard chromosome analysis when necessary. Sometimes follow-up investigations like amniocentesis were performed before a definite prenatal cytogenetic result could be reported. Results In 2389/2476 (96.5%) of the cases, both STC- and LTC-Villi were investigated. Normal STC- with abnormal LTC-Villi results and finally an abnormal fetal karyotype were detected in ten cases (10/2389; 0.42%); in 9/10 of the cases the indication was fetal ultrasound abnormalities. Normal STC- and LTC-Villi and finally an abnormal fetal karyotype were detected in two cases (2/2389; 0.08%). Conclusion The most reliable technique for prenatal diagnosis after chorionic villus sampling (CVS) is the combination of the analysis of both STC- and LTC-Villi to reduce the incidence of false-negative findings to a minimum. In the case of fetal ultrasound abnormalities with a small amount of Villi available, the investigation of LTC-Villi is recommended over that of STC-Villi. Copyright © 2006 John Wiley & Sons, Ltd.
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(Potential) false‐negative diagnoses in chorionic Villi and a review of the literature
Prenatal diagnosis, 2006Co-Authors: Cardi Van Den Berg, Diane Van Opstal, Joke Polak-knook, R. J. H. GaljaardAbstract:Objectives To assess the incidence of (potential) false-negative findings of cytogenetic diagnosis in STC-Villi and/or LTC-Villi and to determine the best strategy for karyotyping chorionic Villi in order to avoid false-negative results. Methods 2476 chorionic villus samples were received for prenatal cytogenetic investigations. Karyotyping was routinely performed on STC- and LTC-Villi preparations by G-banding. Fluorescence in situ hybridization (FISH) analyses were performed in addition to standard chromosome analysis when necessary. Sometimes follow-up investigations like amniocentesis were performed before a definite prenatal cytogenetic result could be reported. Results In 2389/2476 (96.5%) of the cases, both STC- and LTC-Villi were investigated. Normal STC- with abnormal LTC-Villi results and finally an abnormal fetal karyotype were detected in ten cases (10/2389; 0.42%); in 9/10 of the cases the indication was fetal ultrasound abnormalities. Normal STC- and LTC-Villi and finally an abnormal fetal karyotype were detected in two cases (2/2389; 0.08%). Conclusion The most reliable technique for prenatal diagnosis after chorionic villus sampling (CVS) is the combination of the analysis of both STC- and LTC-Villi to reduce the incidence of false-negative findings to a minimum. In the case of fetal ultrasound abnormalities with a small amount of Villi available, the investigation of LTC-Villi is recommended over that of STC-Villi. Copyright © 2006 John Wiley & Sons, Ltd.
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The diagnostic performance of cytogenetic investigation in amniotic fluid cells and chorionic Villi.
Prenatal diagnosis, 2001Co-Authors: Frans J. Los, Cardi Van Den Berg, R. J. H. Galjaard, Hajo I. J. Wildschut, Helen Brandenburg, Nicolette S. Den Hollander, E. M. Schoonderwaldt, Leen Pijpers, Diane Van OpstalAbstract:First-trimester chorionic villus sampling has not reached the popularity of second-trimester amniocentesis in prenatal cytogenetic diagnosis, in contrast to initial expectations. We investigated whether a difference inthe diagnostic performances of cytogenetic investigation in amniotic fluid (AF) cells and chorionic Villi in favour of AF-cells might justify this. Diagnostic performance was measured as laboratory failure rate, karyotype quality (G-band score, rate of follow-up samples, rate of wrong diagnoses), and karyotype representativity (rate of follow-up samples, rate of wrong diagnoses). From 1993–1999, 11 883 AF-samples were investigated (AF-cells). In chorionic Villi, short term culture preparations solely were karyotyped from 1993–1996 (n=3499) (STC-Villi), short and long-term culture preparations simultaneously provided a sufficient amount of tissue being available from 1997 onwards (n=1829) ((STC+LTC)-Villi). Laboratory failure rates were the same after amniocentesis (0.40%) and chorionic villus sampling (0.50%). G-band scores (mean±SD) were equal in AF-cells (373±38.1) and LTC-Villi (364±32.6) but significantly lower in STC-Villi (311±34.6) (p=0.001). Follow-up sampling rates because of quality reasons were the same in AF-cells (0.14%), STC- Villi (0.13%) and (STC+LTC)-Villi (0.11%). Two wrong diagnoses turned up among AF-cells. Follow-up sampling rates because of representativity reasons differed significantly between AF-cells (0.10%), (STC+LTC)-Villi (1.31%), and STC-Villi (1.99%) (p