Freeze-fracture observations on the visceral yolk sac placenta of rats, mice and hamsters
Freeze-fracture observations on the visceral yolk sac placenta of rats, mice and hamsters
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大鼠、小鼠和仓鼠内脏卵黄囊胎盘的冷冻断裂观察
DOI：
10.1007/bf00304993
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
Mark T. Dishaw
中科院分区：
文献类型：
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作者：
S. J. Carpenter;Mark T. Dishaw
通过电子显微镜研究了妊娠后期大鼠、小鼠和仓鼠内脏卵黄囊的冷冻断裂复制品。特别关注确定该胎盘膜的柱状内胚层细胞之间存在的连接特化的类型。在所有三个物种中，在内胚层细胞的连续侧面上都发现了发育良好的小带紧密（闭塞）连接。紧密的连接网络位于直接的亚腔位置，深度为 0.2-0.5 μm，由 2-5 个互连的、约 9 ηm 宽的线（P 面）或浅沟（E 面）的任意点组成。在紧密连接下方的分散部位也观察到了不规则膜内颗粒的斑块状聚集，这是桥粒（粘附斑）的特征。然而，没有遇到间隙（通信）连接的证据。啮齿动物内脏卵黄囊的内胚层细胞已被证明在大分子物质从母体到胎儿系统的选择性转运中发挥核心作用。紧密连接可能通过防止大分子的随机细胞旁通量对这种内胚层细胞功能至关重要。
Freeze-fracture replicas of visceral yolk sac from rats, mice and hamsters in late stages of gestation were studied by electron microscopy. Special attention was directed toward determining the types of junctional specializations that exist between the columnar endoderm cells of this placental membrane. In all three species, well-developed, zonular tight (occluding) junctions were found on the contiguous lateral surfaces of the endoderm cells. The tight junctional network, located in an immediate subluminal position, was from 0.2–0.5 μm in depth and consisted at any point of 2–5, interconnecting, ∼9 ηm wide, strands (P-face) or shallow furrows (E-face). Patch-like aggregations of irregular intramembrane particles, characteristic of desmosomes (maculae adherentes), also were observed at scattered sites below the tight junctions. However, no evidence of gap (communicating) junctions was encountered. The endoderm cells of the rodent visceral yolk sac have been shown to play a central role in the selective transport of macromolecular substances from the maternal to the fetal system. Tight junctions may be vital to this endodermal cell function by preventing random paracellular fluxes of macromolecules.