Rodríguez E M, Oksche A, Montecinos H
Instituto de Histología y Patología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile.
Microsc Res Tech. 2001 Mar 1;52(5):573-90. doi: 10.1002/1097-0029(20010301)52:5<573::AID-JEMT1042>3.0.CO;2-6.
The subcommissural organ (SCO) is a conserved brain gland present throughout the vertebrate phylum. During ontogeny, it is the first secretory structure of the brain to differentiate. In the human, the SCO can be morphologically distinguished in 7- to 8-week-old embryos. The SCO of 3- to 5-month-old fetuses is an active, secretory structure of the brain. However, already in 9-month-old fetuses, the regressive development of the SCO-parenchyma is evident. In 1-year-old infants, the height of the secretory ependymal cells is distinctly reduced and they are grouped in the form of islets that alternate with cuboid non-secretory ependyma. The regression of the SCO continues during childhood, so that at the ninth year of life the specific secretory parenchyma is confined to a few islets of secretory ependymal cells. The human fetal SCO shares the distinct ultrastructural features characterizing the SCO of all other species, namely, a well-developed rough endoplasmic reticulum, with many of its cisternae being dilated and filled with a filamentous material, several Golgi complexes, and secretory granules of variable size, shape, and electron density. The human fetal SCO does not immunoreact with any of the numerous polyclonal and monoclonal antibodies raised against RF-glycoproteins of animal origin. This and the absence of RF in the human led to the conclusion that the human SCO does not secrete RF-glycoproteins. Taking into account the ultrastructural, lectin-histochemical, and immunocytochemical findings, it can be concluded that the human SCO, and most likely the SCO of the anthropoid apes, secrete glyco- protein(s) with a protein backbone of unknown nature, and with a carbohydrate chain similar or identical to that of RF-glycoproteins secreted by the SCO of all other species. These, as yet unidentified, glycoprotein(s) do not aggregate but become soluble in the CSF. Evidence is presented that these CSF-soluble proteins secreted by the human SCO correspond to (1) a 45-kDa compound similar or identical to transthyretin and, (2) a protein of about 500 kDa.
室管膜下器（SCO）是整个脊椎动物门中都存在的一种保守的脑腺。在个体发育过程中，它是大脑中第一个分化的分泌结构。在人类中，7至8周大的胚胎中可在形态上区分出室管膜下器。3至5个月大胎儿的室管膜下器是大脑中一个活跃的分泌结构。然而，在9个月大的胎儿中，室管膜下器实质的退行性发育就已很明显。在1岁婴儿中，分泌性室管膜细胞的高度明显降低，它们聚集成岛状，与立方体形的非分泌性室管膜交替排列。室管膜下器在儿童期持续退化，因此在9岁时，特定的分泌实质仅限于少数分泌性室管膜细胞岛。人类胎儿的室管膜下器具有所有其他物种室管膜下器特有的明显超微结构特征，即发达的粗面内质网，其许多扁平囊泡扩张并充满丝状物质，有几个高尔基体复合体，以及大小、形状和电子密度各异的分泌颗粒。人类胎儿的室管膜下器与针对动物来源的RF糖蛋白产生的众多多克隆和单克隆抗体均无免疫反应。这一点以及人类中不存在RF导致得出结论：人类室管膜下器不分泌RF糖蛋白。考虑到超微结构、凝集素组织化学和免疫细胞化学的研究结果，可以得出结论：人类室管膜下器，很可能还有类人猿的室管膜下器，分泌具有未知性质蛋白质骨架且碳水化合物链与所有其他物种室管膜下器分泌的RF糖蛋白相似或相同的糖蛋白。这些尚未鉴定的糖蛋白不会聚集，而是可溶于脑脊液。有证据表明，人类室管膜下器分泌的这些脑脊液可溶性蛋白对应于：（1）一种与转甲状腺素蛋白相似或相同的45 kDa化合物，以及（2）一种约500 kDa的蛋白质。
