Preston Amanda M, Lindsay Laura A, Murphy Christopher R
School of Medical Sciences (Anatomy and Histology), The University of Sydney, NSW 2006, Australia.
J Morphol. 2006 Jan;267(1):103-8. doi: 10.1002/jmor.10390.
Displacement of uterine epithelial cells is an important aspect of implantation in the rat and other species, allowing invasion of the blastocyst into the endometrial stroma. Desmosomes, which are part of the lateral junctional complex, function in cell-to-cell adhesion, and are therefore likely to be involved in displacement of uterine epithelial cells at the time of implantation. This study used transmission electron microscopy to study rat uterine epithelial cells during the peri-implantation period to investigate the change in the number of structural desmosomes along the lateral plasma membrane of uterine epithelial cells. We found a significant decrease in the number of desmosomes along the entire lateral plasma membrane as pregnancy progressed. Furthermore, there were also significant decreases in the number of desmosomes on the apical portion of the lateral plasma membrane between all days of pregnancy examined. In addition, on day 6 of pregnancy, the time of attachment, desmosomes were larger and seen as "giant desmosomes." For the first time, this study has shown that there is a significant reduction in cell height and actual number of ultrastructurally observable desmosomes at the time of implantation in the rat. It is proposed that this reduction in desmosome number leads to a decrease in lateral adhesion between uterine epithelial cells at the time of implantation, and hence is involved in the loss of uterine epithelial cells to facilitate blastocyst invasion.
子宫上皮细胞的移位是大鼠及其他物种着床过程中的一个重要方面，它使得囊胚能够侵入子宫内膜基质。桥粒是侧连接复合体的一部分，在细胞间黏附中发挥作用，因此很可能在着床时参与子宫上皮细胞的移位。本研究利用透射电子显微镜观察大鼠着床期子宫上皮细胞，以研究子宫上皮细胞外侧质膜上结构桥粒数量的变化。我们发现，随着妊娠的进展，整个外侧质膜上的桥粒数量显著减少。此外，在所检查的妊娠各天中，外侧质膜顶端部分的桥粒数量也显著减少。另外，在妊娠第6天，即着床时，桥粒更大，呈现为“巨型桥粒”。本研究首次表明，在大鼠着床时，细胞高度和超微结构可观察到的桥粒实际数量显著减少。有人提出，桥粒数量的这种减少导致着床时子宫上皮细胞之间的侧向黏附力下降，从而参与子宫上皮细胞的脱落以促进囊胚的侵入。
