Ali K Z, Burton G J, Morad N, Ali M E
Department of Anatomy, King Saud University, Abha Branch College of Medicine, Saudi Arabia.
Placenta. 1996 Nov;17(8):677-82. doi: 10.1016/s0143-4004(96)80018-x.
This study tests the hypothesis that exposure of the placenta to hypobaric hypoxia at altitude results in an altered branching pattern of the villous tree. Histological material from 20 term placentae delivered at altitudes over 3000 m was compared with matched controls from 500 m. Estimates of the mean star volume of intermediate and terminal villous domains were 1.40 x 10(6) microns3 (s.d. 0.63) in the high altitude group and 1.90 x 10(6) microns3 (s.d. 0.34) in the controls (F = 9.07, P < 0.005). The volume fraction of the villous tree occupied by trophoblastic bridges and syncytial knots was 8.1 per cent (s.d. 3.5) in the high altitude group and 3.2 per cent (s.d. 1.6) in the controls (F = 29.45, P < 0.0001). Previous studies have shown that the majority (80 per cent) of bridges are artefacts caused by the plane of section passing tangentially through the trophoblast layer at points of villous bending or branching. The results are, therefore, consistent with the hypothesis that peripheral villi are shorter, knob-like protrusions at high altitude, clustered more closely together. This modified branching pattern was confirmed by scanning electron microscopy. The change in architecture may be due to enhanced angiogenesis stimulated by the lower partial pressure of oxygen prevailing at high altitude.
胎盘在高原低压缺氧环境下会导致绒毛树分支模式改变。将海拔3000米以上分娩的20例足月胎盘的组织学材料与海拔500米的配对对照进行比较。高海拔组中间和终末绒毛区域的平均星体积估计值为1.40×10⁶立方微米（标准差0.63），对照组为1.90×10⁶立方微米（标准差0.34）（F = 9.07，P < 0.005）。高海拔组中由滋养层桥和合体结占据的绒毛树体积分数为8.1%（标准差3.5），对照组为3.2%（标准差1.6）（F = 29.45，P < 0.0001）。先前的研究表明，大多数（80%）的桥是由于切片平面在绒毛弯曲或分支点处切过滋养层而造成的人为假象。因此，这些结果与以下假设一致：在高海拔地区，周边绒毛较短，呈瘤状突起，且聚集更为紧密。这种改变的分支模式通过扫描电子显微镜得到了证实。结构的变化可能是由于高海拔地区较低的氧分压刺激了血管生成增强所致。
