School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK.
Placenta. 2010 Jul;31(7):602-6. doi: 10.1016/j.placenta.2010.04.005. Epub 2010 May 5.
The intrauterine environment has an important influence on placental development. In pre-eclampsia (PE) and intrauterine growth restriction (IUGR), early remodelling of spiral arteries has repercussions for uteroplacental blood flow. The IUGR placenta exhibits compromised growth of villous trees, a smaller intervillous space and a lower diffusive conductance. Here, we test whether or not term placentas associated with PE or IUGR also exhibit changes in structural quantities (notably, sizes and numbers of intervillous pores and villous domains) pertinent to uteroplacental haemodynamics. Paraffin wax sections were sampled at random locations and orientations and structural quantities obtained by combining design-based stereological estimates of total and star volumes with model-based estimates of pore hydraulic diameters. Total volumes of intervillous pores and villi were estimated by point counting, total villous surface by intersection counting and star volumes by measuring point-sampled intercept lengths. Other quantities were derived secondarily and group estimates compared by two-way analysis of variance. We found significant main effects of IUGR but no main or interaction effects involving PE. In IUGR, there were fewer intervillous pores and these had larger hydraulic diameters. IUGR also produced fewer villous domains but these were constant in star volume and villi had a constant mean diameter and volume fraction. We concluded that IUGR compromises placental development by producing intervillous pores and villous trees different in size and shape from those in control and PE pregnancies. Calculations suggest that Darcian conductances in the intervillous space improve in IUGR but, in reality, placental performance is compromised by other physiological and structural constraints including the known decline in diffusive conductances.
子宫内环境对胎盘发育有重要影响。在子痫前期（PE）和宫内生长受限（IUGR）中，螺旋动脉的早期重塑对子宫胎盘血流有影响。IUGR 胎盘表现为绒毛树的生长受损、绒毛间隙更小以及扩散传导率降低。在这里，我们测试与 PE 或 IUGR 相关的足月胎盘是否也表现出与子宫胎盘血液动力学有关的结构数量变化（特别是绒毛间孔和绒毛域的大小和数量）。随机选择石蜡蜡块的位置和方向进行取样，并通过结合基于设计的总星体积的立体学估计与基于模型的孔水力直径估计来获得结构数量。通过点计数估计绒毛间孔和绒毛的总体积，通过交点计数估计总绒毛表面，通过测量点采样的截距长度估计星体积。通过二次衍生其他数量，并通过双向方差分析比较组估计值。我们发现 IUGR 有显著的主要影响，但没有涉及 PE 的主要或相互作用影响。在 IUGR 中，绒毛间孔数量减少，水力直径增大。IUGR 还产生较少的绒毛域，但星体积和绒毛的常数不变，且具有恒定的平均直径和体积分数。我们得出结论，IUGR 通过产生在大小和形状上与对照和 PE 妊娠不同的绒毛间孔和绒毛树来损害胎盘发育。计算表明，IUGR 可改善绒毛间空间的达西传导，但实际上，由于包括已知扩散传导率下降在内的其他生理和结构限制，胎盘性能受到损害。
