内质网是在应用电子显微镜观察细胞之后才开始发现的几乎存在于所有高等动植物细胞内极为重要的细细器。在电镜问世之前的光学显微镜时代,人们已观察到高等动物细胞,特别是肝、胰、肾、唾液腺等蛋白质合成机能旺盛的细胞,在胞质内有被硷性染料所深染的区域。这区域对紫外线显示出有选择地吸收,并为核糖核酸酶 The endoplasmic reticulum is an extremely important foci found in almost all cells of the upper plant and animal, which began to be observed after the cells were observed under an electron microscope. In the era of optical microscopy before the advent of electron microscopy, it has been observed that cells of higher animals, especially those with abundant protein synthesis such as liver, pancreas, kidney, salivary gland and the like, are deeply stained with alkaline dyes in the cytoplasm. This area shows selective absorption of UV light and is a ribonuclease