Department of Obstetrics and Gynecology, Center for Pregnancy and Newborn Research, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
Placenta. 2007 Aug-Sep;28(8-9):783-93. doi: 10.1016/j.placenta.2006.11.012. Epub 2007 Mar 23.
The aims of the present study were to describe the ontogeny of spatial relationships between placental components in baboons and to investigate alterations in these indices following (1) moderate maternal nutrient restriction and (2) administration of glucocorticoids to pregnant baboons. We investigated the effects of glucocorticoids since they have been shown to play a role in the altered fetal growth that accompanies maternal nutrient restriction. Glucocorticoids are also given to pregnant women who threaten premature labor to accelerate fetal lung maturation. A third aim was to compare our findings to those in similar conditions in human pregnancy. Volumetric placental development in the baboon was similar to that in the human, although growth of fetal capillaries was slower over the second half of gestation in baboon than in human placentas. Intervillous space (IVS) and villous star volumes were halved at the end of gestation compared to the middle of gestation, as described in the human placenta. When mothers were fed 70% of feed eaten by controls fed ad libitum, placental volumetric structure was unchanged at mid-gestation but was altered by the end of gestation when placental weight, but not fetal weight or length, was decreased. At the end of gestation villous volume and surface area, capillary surface area, and the villous isomorphic coefficient were all decreased, In contrast, IVS hydraulic diameter was increased. All parameters were similar in pregnancies with male and female fetuses, with the exception of fetal capillary volume, which was unchanged in pooled samples and those from male fetuses, but decreased in pregnancies with female fetuses. Glucocorticoid administration during the second half of gestation did not produce any changes in the measured indices of placental composition. In summary, these changes in placental structure, associated with maternal nutrient restriction, would all act to decrease placental transport of nutrients. The influence of MNR on villous capillarization depends on fetal gender.
本研究的目的是描述狒狒胎盘成分之间空间关系的发育，并研究以下情况对这些指数的改变：（1）中度母体营养限制和（2）给怀孕的狒狒施用糖皮质激素。我们研究了糖皮质激素的影响，因为它们已被证明在伴随母体营养限制的胎儿生长改变中起作用。糖皮质激素也被给予有早产威胁的孕妇，以加速胎儿肺成熟。第三个目的是将我们的发现与人类妊娠中的类似情况进行比较。尽管在狒狒胎盘中，妊娠后半期胎儿毛细血管的生长速度比人类胎盘慢，但狒狒胎盘的体积发育与人类相似。与妊娠中期相比，妊娠末期的绒毛间空间（IVS）和绒毛星形体积减少了一半，如人类胎盘所述。当母亲以 70%的自由进食对照组的饲料进食时，妊娠中期胎盘的体积结构没有改变，但在妊娠末期胎盘重量（而不是胎儿重量或长度）减少时，胎盘的体积结构发生了改变。在妊娠末期，绒毛体积和表面积、毛细血管表面积和绒毛同型系数均降低，而 IVS 水力直径增加。除了胎儿毛细血管体积在合并样本和雄性胎儿中保持不变，但在雌性胎儿中降低外，所有参数在具有雄性和雌性胎儿的妊娠中均相似。妊娠中期给予糖皮质激素不会导致胎盘组成的测量指数发生任何变化。总之，这些与母体营养限制相关的胎盘结构变化都会降低胎盘对营养物质的转运。MNR 对绒毛血管化的影响取决于胎儿性别。
