Metz J
Anat Embryol (Berl). 1980;159(3):289-305. doi: 10.1007/BF00317652.
The differentiation of chorionic layers II and III and alterations of intercellular junctions within the developing placental labyrinth were investigated in rats. Between the 14th and 16th day of gestation, the trabecular structures of the labyrinth alter and increasing numbers of primary, secondary, and tertiary lamellae develop. Trophoblastic layer I remains multicellular. Layer III rearranges and cytoplasmic fusions result in a continuous cytoplasmic barrier intervening between the already syncytial trophoblastic layer II and fetal capillaries. Simultaneously, most of the "undifferentiated" cells within the labyrinth disappear. Thin sectioning anf freeze-fracturing reveal multiple images of intercellular junctions, particularly gap and tight junctions in the cellular and syncytial parts of layers II and III. Continuous and regularly arranged tight junctions occur as well as fragmented structures which are spaced irregularly. Gap junctions are occasionally found between the juxtasinusoidal regions of layers II and III on the 14th day. More often they occur within restricted areas near the center of the trabeculae, integrated within extensive tight junctional strands. Gap junctions increase in later stages of pregnancy and eventually become distributed between the interfaces of layers II and III in the primary lamellae.
在大鼠中研究了绒毛膜层II和III的分化以及发育中的胎盘迷路内细胞间连接的变化。在妊娠第14天至16天之间，迷路的小梁结构发生改变，并且越来越多的初级、次级和三级板层发育。滋养层I保持多细胞状态。层III重新排列，细胞质融合形成一个连续的细胞质屏障，介于已经形成合体的滋养层II和胎儿毛细血管之间。同时，迷路内大多数“未分化”细胞消失。薄切片和冷冻断裂显示了细胞间连接的多种图像，特别是在层II和III的细胞和合体部分中的间隙连接和紧密连接。出现了连续且规则排列的紧密连接以及不规则间隔的片段化结构。在第14天，间隙连接偶尔出现在层II和III的近窦区域之间。它们更常出现在小梁中心附近的受限区域内，整合在广泛的紧密连接链中。间隙连接在妊娠后期增加，并最终分布在初级板层中层II和III的界面之间。
