The effects of hormones on trafficking in the endolymphatic sac

为了研究内淋巴囊(ES)中间部上皮细胞的内吞作用特性，我们将阳离子铁蛋白(CF)、微量过氧化物酶(MPO)和辣根过氧化物酶(HRP)作为内吞示踪剂注入内淋巴囊(ES)的内淋巴间隙。输液30min后固定组织，用透射电子显微镜观察组织中HRP、MOP和CF的分布。示踪剂输注30min后测定结果如下。对于CF，内吞作用根据ES面积的不同而表现出不同的活性。在一个区域，上皮细胞内几乎没有观察到CF，而在另一个区域，在上皮细胞内观察到了CF。载药囊泡主要为包膜囊泡。这些结果提示，人工内淋巴囊内淋巴注入CF可能不会刺激ES的整个信号系统。关于HRP，它结合在顶膜上，在囊泡和分选内小体中观察到。这些小泡的直径有两种类型：一种直径较小(小于200 nm)，另一种直径较大(大于200 nm)，来源于巨噬细胞增多症。关于MPO，小泡中的MPO比HRP少得多。我们讨论了这些示踪剂中不同的内吞作用活性，并认为大分子物质，即HRP，可能刺激液相内吞作用和/或吸附胞吞作用。

To investigate the properties of endocytosis of the epithelial cells in the intermediate portion of the endolymphatic sac (ES), we infused cationized ferritin (CF), microperoxidase (MPO), and horseradish peroxidase (HRP), as endocytosis tracers, into the endolymphatic space of the ES. Thirty minutes after infusion, the tissues were fixed and the distributions of HRP, MOP and CF were observed by transmission electron microscopy. The results at 30 minutes after tracer infusion were as follows. Concerning CF, endocytosis showed different activity depending on the area of the ES. In one area, CF was hardly observed within the epithelial cells, while in another area, it was observed within the epithelial cells. The CF-loaded vesicles were mainly coated vesicles. These results suggested that infusion of the artificial endolymphatic sac endolymph with CF may not stimulate the whole signal system of the ES. Concerning HRP, it bound to the apical membrane and was observed in the vesicles and the sorting endosomes. The diameters of these vesicles were of two types : one had a smaller diameter (less than 200nm), while the other had a larger diameter (over 200nm) and originated from macropinocytosis. Concerning MPO, it was much less observed in the vesicles than HRP. We discuss the different activities of endocytosis among these tracers, and suggest that a large molecular weight substance, i.e.HRP, might stimulate the fluid-phase endocytosis and/or adsorptive pinocytosis.