McRae A C
Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
J Reprod Fertil. 1988 Mar;82(2):857-73. doi: 10.1530/jrf.0.0820857.
The concept of a blood-tissue barrier defines the rates at which matter exchanges among the vascular and extravascular fluids of the tissue. The remarkably slow rates at which substances such as mannitol (Mr 182) enter uterine fluid from plasma demonstrate the existence of a blood-uterine lumen barrier. Available evidence indicates that the uterine microvascular endothelium and the uterine epithelium behave as lipoid layers interrupted by water-filled channels. Furthermore, both cell layers appear to select actively certain substances over others for exchange with opposing extracellular fluids. In contrast to these similarities, the uterine epithelium and endothelium differ considerably with regard to restrictiveness. For most substances the primary rate-limiting boundary between blood and the uterine lumen is the epithelium. The extracellular fluid compartments of the lumen and endometrium are also influenced by the internalization and release of materials into and out of intracellular compartments including those of the stromal and migratory cells of the endometrium, the epithelium and the developing conceptus. Considerable evidence suggests that the luminal milieu of the developing embryo is created and maintained by the transport and permeability properties of the blood-uterine lumen barrier in conjunction with the cellular activities of the endometrium and embryo. This milieu probably fulfils the informational and nutritional needs of the developing embryo.
血组织屏障的概念定义了物质在组织的血管内液和血管外液之间交换的速率。甘露醇（分子量182）等物质从血浆进入子宫液的速率非常缓慢，这证明了血 - 子宫腔屏障的存在。现有证据表明，子宫微血管内皮和子宫上皮表现为被充满水的通道中断的脂质层。此外，这两层细胞似乎会主动选择某些物质而非其他物质，以便与相对的细胞外液进行交换。与这些相似之处形成对比的是，子宫上皮和内皮在限制性方面有很大差异。对于大多数物质而言，血液与子宫腔之间的主要限速边界是上皮。子宫腔和子宫内膜的细胞外液区室也受到物质进出细胞内区室（包括子宫内膜的基质细胞和游走细胞、上皮细胞以及发育中的孕体的细胞内区室）的内化和释放的影响。大量证据表明，发育中胚胎的腔内环境是由血 - 子宫腔屏障的转运和通透性特性以及子宫内膜和胚胎的细胞活动共同创造和维持的。这种环境可能满足发育中胚胎的信息和营养需求。
