The Pattern of Villous Variability in the Normal Placenta

Fox, H.

doi:10.1111/j.1471-0528.1964.tb04352.x

Cited by 55 publications

(8 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, measurements of antioxidant enzyme expression and activity in villous tissues sampled from different sites within lobules support this hypothesis (Hempstock et al 2003a). It is also notable that dilated capillary sinusoids and vasculosyncytial membranes are more prominent in the peripheral regions of a lobule, where oxygen concentrations are predicted to be the lowest (Fox 1964, Critchley & Burton 1987). …”

Section: Angiopoietinsmentioning

confidence: 89%

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

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

show abstract

Section: Angiopoietinsmentioning

confidence: 89%

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

show abstract

“…Variations in villous morphology, and in particular in the occurrence of vasculo‐syncytial membranes between these regions, have been reported (Fox 1964; Teasdale 1978). Critchley and Burton (1987) showed a reduction in the harmonic mean thickness of the villous membrane in the more peripheral parts of the lobule; they proposed this to be an adaptation to the lower prevailing oxygen tension in that region.…”

Section: Discussionmentioning

confidence: 99%

The effects of maternal vascular pressure on the dimensions of the placental capillaries

Karimu

Burton

1994

BJOG

View full text Add to dashboard Cite

Objective The study sought stereological evidence for the sluice flow phenomenon in the human term placenta. Design Two series of experiments were conducted on Caesarian delivered placentae. In both, two fetal arteries were cannulated and perfused. In the first series, five placentae were perfusion‐fixed under arterial pressures of 40 mmHg and 60 mmHg, and an external pressure of 10 mmHg in the intervillous space. In the second series, five placentae were perfusion‐fixed at arterial pressures of 70 mmHg and 90 mmHg with an external pressure of 30 mmHg. Stereological estimates relating to the size of the capillaries and the thickness of the villous membrane were then made. Results In each series, as the arterial pressure rose, there was an increase in the volume fraction and surface area of the fetal capillaries, and a concomittant decrease in the mean thickness of the villous membrane. These changes were negated as the external pressure rose, indicating the importance of the pressure differential between the capillary lumen and the intervillous space in determining the dimensions of the fetal capillaries. Conclusions The study demonstrated that placental capillaries are elastic and hence deformable. If a sufficiently high pressure is generated in the intervillous space, they may therefore be compressed. This may explain the increase in umbilical vascular resistance demonstrated by doppler studies in pregnant women scanned in the supine position. In this situation the venous drainage from the intervillous space is believed to be impeded by the gravid uterus compressing the inferior vena cava.

show abstract

“…Lack of consideration of the normal regional structural variations in chorion villi probably accounts for the discrepancies in results between different studies of placentas from diabetic women (1, 2, 8, 14.22). In the present study, an effort was made to avoid this source of error by choosing defined regions of a defined cotyledon, as discussed by Fox (15). The tissue used for the present study was always taken from a plane midway between the fetal and maternal surfaces, to avoid the differences in villous structure known to exist near these surfaces (4, 34,35).…”

Section: Discussionmentioning

confidence: 99%

“…Variability in appearance and structure of the villi follows a uniform pattern throughout a normal pregnancy (15,18). Comparison with placentas from abnormal pregnancies requires consideration of the regional differences.…”

Section: Methodsmentioning

confidence: 99%

Villous structure in different parts of the cotyledon in placentas of insulin‐dependent diabetic women

Björk

Persson

1984

Acta Obstet Gynecol Scand

View full text Add to dashboard Cite

Placentas from 13 insulin-dependent diabetic mothers and 10 non-diabetics were compared by means of photographic planimetry. The material was investigated in fresh state and obtained from three well-defined areas within a cotyledon, central, intermediate and lateral regions. Length and area of the villi in each region were calculated. The non-diabetics showed a consistent organization of the cotyledon, with increasing villous length towards the periphery. The surface areas increased with increasing length. In placentas of diabetic mothers, this organization was disrupted. The villi were of even length throughout the cotyledon. The average length of a villus in the diabetic group did not differ from the average length in the control group. Despite this fact, the average surface area in the diabetic was greater than that in the controls. This increased surface area was due to increased branching of peripheral villi in the diabetic group. The degree of blood glucose control of the diabetic mothers was assessed by the day-to-day variation in maternal blood glucose levels ( MODD ) for periods 12th to 32nd week and 32nd week to term and by "pregnancy glucose value", i.e. the mean of four consecutive daily blood glucose levels from the 32nd week of gestation to term. Only MODD values based on blood glucose values from 12th to 32nd week of gestation were correlated to the villous surface area. The greater the blood glucose variability, the greater was the surface area.

show abstract

The Pattern of Villous Variability in the Normal Placenta

Cited by 55 publications

References 15 publications

Regulation of vascular growth and function in the human placenta

Regulation of vascular growth and function in the human placenta

The effects of maternal vascular pressure on the dimensions of the placental capillaries

Villous structure in different parts of the cotyledon in placentas of insulin‐dependent diabetic women

Contact Info

Product

Resources

About