Salamat M, Götz W, Horster A, Janotte B, Herken R
Zentrum Anatomie, Universität Göttingen, Germany.
Cell Tissue Res. 1993 May;272(2):375-81. doi: 10.1007/BF00302742.
In the present investigation, we examined the role of trophoblast and parietal endoderm cells in the synthesis of carbohydrate-containing components of Reichert's membrane. To eliminate the function of Reichert's membrane as a filter between maternal and embryonal tissues we carried out our examination under in vitro conditions. Parietal yolk sac from mouse embryos on day 9 post coitum (p.c.) were cultivated for 0 to 5 days. Because tannic acid enables a complex formation between carbohydrates and osmium we chose the fixation with this acid for the ultrastructural study. Electron microscopy showed that for assembly of Reichert's membrane, trophoblast cells produce and then release components that were detected as tannic acid-positive granules both in the Reichert's membrane and in the vacuoles of the trophoblast cells. To localize specific carbohydrates we used postembedding-gold-lectin histochemistry on LR-GoldR-embedded tissues. Strong binding sites for the lectins WGA (Triticum vulgare), RCA I (Ricinus communis) and Con A (Canavalia ensiformis) were observed in Reichert's membrane and trophoblast cells but not in the parietal endoderm cells. The LTA (Lotus tetragonolobus)-binding pattern was positive in the membrane and its adjacent cells but that of the LFA (Limax flavus) was negative in the parietal endoderm cells and very weak in Reichert's membrane and trophoblast cells. Our results demonstrate that trophoblast cells are involved in the construction of Reichert's membrane through the production and release of specific glycoconjugates.
在本研究中，我们检测了滋养层细胞和壁内胚层细胞在合成赖歇特氏膜含碳水化合物成分中的作用。为消除赖歇特氏膜作为母体和胚胎组织之间过滤器的功能，我们在体外条件下进行了检测。取自交配后第9天（p.c.）小鼠胚胎的壁层卵黄囊培养0至5天。由于单宁酸能使碳水化合物与锇形成复合物，我们选择用这种酸固定用于超微结构研究。电子显微镜显示，为组装赖歇特氏膜，滋养层细胞产生并释放一些成分，这些成分在赖歇特氏膜和滋养层细胞的液泡中均被检测为单宁酸阳性颗粒。为定位特定碳水化合物，我们对LR-GoldR包埋的组织进行了包埋后金标记凝集素组织化学分析。在赖歇特氏膜和滋养层细胞中观察到了凝集素WGA（普通小麦）、RCA I（蓖麻）和Con A（刀豆）的强结合位点，但在壁内胚层细胞中未观察到。LTA（四角豆）的结合模式在膜及其相邻细胞中呈阳性，而LFA（黄蛞蝓）的结合模式在壁内胚层细胞中呈阴性，在赖歇特氏膜和滋养层细胞中非常弱。我们的结果表明，滋养层细胞通过产生和释放特定的糖缀合物参与赖歇特氏膜的构建。
