King B F, Blankenship T N
Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis 95616-8643.
Anat Rec. 1994 Apr;238(4):498-506. doi: 10.1002/ar.1092380409.
Anchoring villi and cytotrophoblastic cell columns are important structural components involved in placental morphogenesis. We have previously described the presence of an unusual basement membrane-like layer (BMLL) that separates these placental compartments. The purpose of the present study was to identify developmental changes in the ultrastructure of the BMLL and to assess its changes in extracellular matrix composition over the course of gestation.
Conventional techniques were used to examine macaque placental tissue by transmission electron microscopy. Standard immunoperoxidase methods were used to identify type IV collagen, laminin and fibronectin in paraffin sections.
Until day 35 of gestation the BMLL was 70-100 nm thick and appeared similar to basement membranes seen in other regions of the villus, although it usually lacked a lamina lucida along the surface adjacent to the cytotrophoblast cells. Immunohistochemistry revealed the presence of laminin and type IV collagen in the BMLL. By 53 days of gestation the BMLL had hypertrophied at the junction of the anchoring villus and cell column, measuring 2,000-5,000 nm in thickness. The BMLL retained immunoreactivity for laminin and type IV collagen. Ultrastructural examination revealed the presence of a new component in the form of 10 nm microfibrils. By 89 days of gestation the BMLL was not reactive for laminin or type IV collagen but otherwise maintained the structural organization seen at 53 days. No additional changes were observed in the BMLL during late pregnancy.
The BMLL is a distinct extracellular matrix region that separates the distal aspect of the anchoring villus from the proximal portion of the cell columns. Evidence indicates that adjacent cytotrophoblast plays a prominent role in the production of the BMLL. The BMLL may serve to organize this complex tissue by separating fetal mesenchyme from cytotrophoblast cells that are proliferating, differentiating, and migrating. Modifications to the composition of the BMLL may indicate changes in the role this matrix plays in the development of the placenta.
固定绒毛和细胞滋养层细胞柱是参与胎盘形态发生的重要结构成分。我们之前曾描述过一种不寻常的基底膜样层（BMLL），它分隔了这些胎盘结构。本研究的目的是确定BMLL超微结构的发育变化，并评估其在妊娠过程中细胞外基质成分的变化。
采用传统技术通过透射电子显微镜检查猕猴胎盘组织。使用标准免疫过氧化物酶方法在石蜡切片中鉴定IV型胶原、层粘连蛋白和纤连蛋白。
在妊娠第35天之前，BMLL厚度为70 - 100纳米，外观与绒毛其他区域所见的基底膜相似，尽管其在靠近细胞滋养层细胞的表面通常缺乏透明板。免疫组织化学显示BMLL中存在层粘连蛋白和IV型胶原。到妊娠53天时，BMLL在固定绒毛与细胞柱的交界处增厚，厚度达2000 - 5000纳米。BMLL对层粘连蛋白和IV型胶原仍保持免疫反应性。超微结构检查显示存在一种10纳米微纤维形式的新成分。到妊娠89天时，BMLL对层粘连蛋白或IV型胶原无反应，但在其他方面保持了53天时所见的结构组织。妊娠晚期在BMLL中未观察到其他变化。
BMLL是一个独特的细胞外基质区域，它将固定绒毛的远端与细胞柱的近端分隔开。有证据表明相邻的细胞滋养层在BMLL的产生中起重要作用。BMLL可能通过将胎儿间充质与正在增殖、分化和迁移的细胞滋养层细胞分隔开来，对这种复杂组织起到组织作用。BMLL成分的改变可能表明该基质在胎盘发育中所起作用的变化。
