Schöbitz K, Gonzalez C, Peruzzo B, Yulis C R, Rodríguez E M
Instituto de Histología y Patología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile.
Microsc Res Tech. 2001 Mar 1;52(5):496-509. doi: 10.1002/1097-0029(20010301)52:5<496::AID-JEMT1035>3.0.CO;2-R.
The subcommissural organ (SCO) is a brain circumventricular organ formed by ependymal and hypendymal secretory cells. It secretes glycoproteins into the cerebrospinal fluid of the third ventricle where they condense into a thread-like structure known as Reissner's fiber (RF). The present study was designed to investigate whether or not the bovine SCO continues to synthesize and release glycoproteins after a long-term culture. Cultured explants of SCO survive for several months. The content of the secretory granules present in the cultured ependymocytes displayed immunoreactive and lectin-binding properties similar to those of the core glycosylated glycoproteins found in the bovine SCO. The explants actively incorporated (35)S-cysteine. In the cultured ependymocytes, the pattern of distribution of the radioactive label and that of the immunoreactive secretory material was similar, thus indicating that this material has been synthesized during culture. At the ultrastructural level, the cultured tissue exhibited a high degree of differentiation comparable to that of the bovine SCO in situ. A striking finding was the observation of similar results when cerebrospinal fluid was used as a culture medium. The addition of antibodies against RF-glycoproteins into the culture medium allowed visualization, by means of different immunocytochemistry protocols, deposits of extracellular immunoreactive secretory material on the free surface of the cultured ependymocytes, indicating that release of secretory glycoproteins into the culture medium does occur. Primary culture of dispersed SCO ependymocytes, obtained either from fresh or organ cultured bovine SCO, showed that these cells release RF-glycoproteins that aggregate in the vicinity of each cell. The present investigation has shown that: (1) two types of secretory ependymocytes become evident in the cultured SCO; (2) under culture conditions, the SCO cells increase their secretory activity; (3) explants of bovine SCO synthesize RF-glycoproteins and release them to the culture medium; (4) after release these proteins aggregate but do not form a RF; (5) a pulse of anti-RF antibodies into the culture medium blocks the secretion of RF-glycoproteins for several days.
室管膜下器官（SCO）是一种由室管膜和室管膜下分泌细胞形成的脑室内器官。它将糖蛋白分泌到第三脑室的脑脊液中，在那里它们凝结成一种线状结构，称为赖氏纤维（RF）。本研究旨在调查长期培养后牛SCO是否继续合成和释放糖蛋白。培养的SCO外植体可存活数月。培养的室管膜细胞中存在的分泌颗粒的内容物显示出与牛SCO中发现的核心糖基化糖蛋白相似的免疫反应性和凝集素结合特性。外植体积极摄取（35）S-半胱氨酸。在培养的室管膜细胞中，放射性标记物的分布模式与免疫反应性分泌物质的分布模式相似，因此表明该物质是在培养过程中合成的。在超微结构水平上，培养的组织表现出与原位牛SCO相当的高度分化。一个显著的发现是，当使用脑脊液作为培养基时，观察到了类似的结果。向培养基中添加针对RF糖蛋白的抗体，通过不同的免疫细胞化学方法，可以观察到培养的室管膜细胞自由表面上细胞外免疫反应性分泌物质的沉积，表明分泌性糖蛋白确实释放到了培养基中。从新鲜或器官培养的牛SCO中获得的分散的SCO室管膜细胞的原代培养表明，这些细胞释放RF糖蛋白，这些糖蛋白在每个细胞附近聚集。本研究表明：（1）在培养的SCO中，两种类型的分泌性室管膜细胞变得明显；（2）在培养条件下，SCO细胞增加其分泌活性；（3）牛SCO外植体合成RF糖蛋白并将其释放到培养基中；（4）释放后，这些蛋白质聚集但不形成RF；（5）向培养基中注入抗RF抗体脉冲可在数天内阻断RF糖蛋白的分泌。
