Tanimura F, Morioka H, Murakami Y
Department of Otolaryngology, Municipal Yamashiro Hospital, Kyoto, Japan.
Eur Arch Otorhinolaryngol. 1995;252(4):249-54. doi: 10.1007/BF00179920.
To evaluate the protective function of the mucous blanket (MB) against lectin substances, we examined at the ultrastructural level whether intraluminal colloidal gold-labelled wheat germ agglutinin (WGA) could enter the MB-covered epithelial cell surface of the guinea pig tubotympanic mucosa. Post-embedding staining with WGA/gold on thin tissue sections was done in parallel for comparison. The cell surface glycoconjugate of the eustachian tubal and transitional epithelium had a typical bilayered structure: the outer MB and the microvilli-associated glycocalyx (MAG), which were interposed by the interciliary fluid zone. In squamous epithelium of the distal middle ear, the MB adhered to the MAG, thereby forming a monolayered coat of glycoconjugates at the cell surface. In the pre-embedding staining, WGA/gold did not bind with the MB and MAG in the eustachian tube, and exclusively bound with MB in the transitional area. Direct binding was also found with MAG and the apical plasmic membrane in the squamous epithelium. These findings indicate that MAG is occluded by MB lined with the interciliary fluid zone for luminal access of lectin at the proximal lumina of the tubotympanic epithelium. It is also suggested that MB existing at two sites possesses a different WGA-binding capacity: shielding as a "dust cover" in the eustachian tube and entrapping as a "flypaper" against lectin in the transitional area of the middle ear.
为了评估黏液毯（MB）对凝集素物质的保护作用，我们在超微结构水平上研究了管腔内胶体金标记的麦胚凝集素（WGA）是否能够进入豚鼠咽鼓管鼓室黏膜覆盖有MB的上皮细胞表面。同时，对薄组织切片进行了WGA/金的包埋后染色以作比较。咽鼓管和移行上皮的细胞表面糖缀合物具有典型的双层结构：外层的MB和与微绒毛相关的糖萼（MAG），它们被睫间液区隔开。在中耳远端的鳞状上皮中，MB附着于MAG，从而在细胞表面形成一层糖缀合物涂层。在包埋前染色中，WGA/金在咽鼓管中不与MB和MAG结合，而仅在移行区与MB结合。在鳞状上皮中还发现MAG与顶端质膜直接结合。这些发现表明，在咽鼓管鼓室上皮近端管腔处，MAG被衬有睫间液区的MB所封闭，以阻止凝集素进入管腔。还表明存在于两个部位的MB具有不同的WGA结合能力：在咽鼓管中作为“防尘罩”起屏蔽作用，而在中耳移行区作为“捕蝇纸”捕获凝集素。
