The development of capillaries in the villi of early human placentas

Dempsey, Edward W.

doi:10.1002/aja.1001340207

Cited by 74 publications

(44 citation statements)

References 14 publications

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“…Hemangioblastic cells differentiate in situ and form small clumps or cords of cells lying just beneath the trophoblastic epithelium. These precursor endothelial cells are united by either desmosomes or tight junctions, and the cords gradually acquire lumens and unite to form vessels (Dempsey 1972, Demir et al 1989. The first signs of lumen formation are seen around 23 days pc, and immunohistochemical and morphological evidences suggest that apoptosis is involved in the process (Tertemiz et al 2005).…”

Section: Morphological Aspects Of Vascular Developmentmentioning

confidence: 94%

Regulation of vascular growth and function in the human placenta

Burton¹,

Charnock-Jones²,

Jauniaux³

2009

Reproduction

306

189

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During the course of 9 months, the human placenta develops into a highly vascular organ. Vasculogenesis starts during the third week post-conception. Hemangioblastic cell cords differentiate in situ from mesenchymal cells in the villous cores, most probably under the influence of vascular endothelial growth factor (VEGFA) secreted by the overlying trophoblast. The cords elongate through proliferation and cell recruitment, and connect with the vasculature of the developing fetus. A feto-placental circulation starts around 8 weeks of gestation. Elongation of the capillaries outstrips that of the containing villi, leading to looping of the vessels. The obtrusion of both capillary loops and new sprouts results in the formation of terminal villi. Branching and non-branching angiogenesis therefore play key roles in villous morphogenesis throughout pregnancy. Maternal circulating levels of VEGFA and placental growth factor vary across normal pregnancy, and in complicated pregnancies. Determining the impact of these changes on placental angiogenesis is difficult, as the relationship between levels of factors in the maternal circulation and their effects on fetal vessels within the placenta remains unclear. Furthermore, the trophoblast secretes large quantities of soluble receptors capable of binding both growth factors, influencing their bioavailability. Villous endothelial cells are prone to oxidative stress, which activates the apoptotic cascade. Oxidative stress associated with onset of the maternal circulation, and with incomplete conversion of the spiral arteries in pathological pregnancies, plays an important role in sculpting the villous tree. Suppression of placental angiogenesis results in impoverished development of the placenta, leading ultimately to fetal growth restriction. Reproduction (2009) 138 895-902

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Section: Morphological Aspects Of Vascular Developmentmentioning

confidence: 94%

Regulation of vascular growth and function in the human placenta

Burton¹,

Charnock-Jones²,

Jauniaux³

2009

Reproduction

306

189

View full text Add to dashboard Cite

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“…As it became evident from the publication by Dempsey [ 1972], it is nearly impossible to collect a complete series of exactly defined early human specimens under appropriate conditions for electron microscopy as was possible for the rhesus monkey. We have collected our material over a period of several years with combined efforts of several universities in Turkey.…”

Section: Introductionmentioning

confidence: 99%

“…Since both processes take place during placental development we will follow this nomenclature. The classical study in this field is that of Dempsey [1972] describing the ultrastruc ture of vasculogenesis in early human villi. From this paper the related problems became evident.…”

Section: Introductionmentioning

confidence: 99%

Fetal Vasculogenesis and Angiogenesis in Human Placental Villi

Demir

Kaufmann

Castellucci

et al. 1989

Cells Tissues Organs

241

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Placental villi of 5 exactly defined early human specimens ranging from day 21 post conception (p.c.) until day 42 p.c. and from an additional 43 specimens from about 5 to 40 weeks menstrual age have been analyzed ultrastructurally with regard to fetal vasculogenesis and angiogenesis. The following results were obtained: The first cells differentiating at day 21 p.c. probably originating from mesenchymal precursors, are macrophage-like cells. At almost the same time, mesenchymal cells transform into haemangioblastic cell cords which are the forerunners of the capillary endothelium and haematopoietic stem cells. A third cell population related to the fetal circulatory system and derived from the mesenchymal cells are presumptive pericytes. Capillary formation takes place by the aggregation of haemangioblastic cells which are attached to each other by intercellular junctions. The lumen is formed by the dehiscence of the intercellular clefts. A capillary basal lamina cannot be detected earlier than in the last trimester. In this last period of gestation fetal villous angiogenesis takes place by the proliferation of the existing endothelium and pericytes rather than via haemangioblastic cells.

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“…The ultrastructure of the chorionic villus stroma has been studied by many resear chers [Rhodin and Terzakis, 1962;Terzakis, 1963;Lis ter, 1963;Becker and Seifert, 1963;Boyd and Hamilton, 1967;Herbst et al, 1969;Tedde, 1970;Demir, 1980]. A number of studies also focussed on special aspects; for example, the development and differentiation of the vessels in the chorionic villus stroma have been investi gated by Becker and Seifert [1963], Dempsey [1972], and Nikolov and Schiebler [1973]. In addition, the Hof bauer cells, which are very interesting cells of the villus stroma, have been studied by numerous investigators [Punigel and Anh, 1964;Wynn, 1967;Krauer, 1969;Vacek, 1970;Enders and King, 1970].…”

Section: Introductionmentioning

confidence: 99%

Some New Findings about Hofbauer Cells in the Chorionic Villi of the Human Placenta

Demir

Erbengi

1984

Cells Tissues Organs

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The cytological structure of the Hofbauer cells was investigated in human placentas of the first and second trimesters of gestation. These cells are found in the stromal channel system of the chorionic villi core. Their walls, which are supported by collagen fiber bundles, are produced by reticulum cells and fibroblasts. The cytoplasmic processes of the Hofbauer cells are in contact with the walls of the channels without being associated with them by desmosomal complexes. Some of these cells have features in common with macrophages, such as cytoplasmic processes, larger vacuoles, many pinocytotic vesicles and intracytoplasmic granules. This system of vacuoles and vesicles enables micropinocytotic activity and phagocytosis. This type of Hofbauer cell resembles the typical macrophages. These cells may play a role in the regulation of stromal water content, transportation of ions and the flow of interstitial fluid. The most original finding of this study are long tubes observed in some Hofbauer cells and extending between the nucleus and the extracellular ground substance through the cytoplasm. One of these tubular formations resembles a cilium in structure with three limiting membranes and is filled with a slightly electron-dense substance. This type of Hofbauer cell may transport information between the nucleus and the extracellular ground substance by means of these tubular structures.

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The development of capillaries in the villi of early human placentas

Cited by 74 publications

References 14 publications

Regulation of vascular growth and function in the human placenta

Regulation of vascular growth and function in the human placenta

Fetal Vasculogenesis and Angiogenesis in Human Placental Villi

Some New Findings about Hofbauer Cells in the Chorionic Villi of the Human Placenta

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