The effects of hormones on trafficking in the endolymphatic sac

为了研究内淋巴囊（ES）中间部上皮细胞内吞作用的性质，我们将阳离子化铁蛋白（CF）、微过氧化物酶（MPO）和辣根过氧化物酶（HRP）作为内吞作用示踪剂注入ES的内淋巴间隙。灌注后30 min，固定组织，透射电镜观察HRP、MOP和CF的分布。示踪剂输注后30分钟的结果如下。关于CF，根据ES的面积，内吞作用表现出不同的活性。在一个区域中，在上皮细胞内几乎观察不到CF，而在另一个区域中，在上皮细胞内观察到CF。载CF的囊泡主要为包被囊泡。结果提示，人工内淋巴囊内注入CF可能并不能刺激ES的整个信号系统。关于HRP，它结合到顶膜，并在囊泡和分选内体中观察到。这些囊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），来源于巨胞饮。MPO在囊泡中的表达明显少于HRP。我们讨论了这些示踪剂之间的不同活动的内吞作用，并建议，一个大分子量的物质，即HRP，可能会刺激液相内吞和/或吸附胞饮。

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.