胎盘在胎儿容量控制的整合生理学中的作用。
The placenta in the integrated physiology of fetal volume control.
作者信息
Faber J Job, Anderson Debra F
机构信息
Heart Research Center, School of Medicine, OHSU, Portland, OR, USA.
出版信息
Int J Dev Biol. 2010;54(2-3):391-6. doi: 10.1387/ijdb.082796jf.
Almost all water that enters the conceptus of the sheep enters via the placenta. The forces that drive water are hydrostatic and osmotic. The placental channels that allow water to cross into the fetus have not been identified by microanatomic means. Although an "equivalent pore" system can account for the diffusional entry of small hydrophilic solutes, it can be calculated that the filtration coefficient of this system is too small to account for the demonstrated trans-placental water flows. It is possible that a second much less numerous system of large pores permits the flow of water, but that is by no means certain. The placenta does not control the amount of water that enters the conceptus; nor does any other single fetal structure. And water entry is not dependent on the volume of water already present. However, the combined physiological properties of the fetal heart, kidneys, somatic tissues and placenta constitute a consistent explanation of fetal water volume control.
几乎所有进入绵羊胚胎的水都是通过胎盘进入的。驱动水流动的力量是流体静力和渗透力。通过微观解剖手段尚未确定允许水进入胎儿的胎盘通道。尽管“等效孔”系统可以解释亲水性小溶质的扩散进入，但可以计算出该系统的滤过系数太小，无法解释已证实的跨胎盘水流。有可能存在第二个数量少得多的大孔系统允许水流动，但这绝不能确定。胎盘并不控制进入胚胎的水量；其他任何单个胎儿结构也不能控制。而且水的进入并不依赖于已存在的水量。然而，胎儿心脏、肾脏、躯体组织和胎盘的综合生理特性构成了对胎儿水量控制的连贯解释。
Zotero 插件