柯林斯詞典epithelium /??p??θi?l??m/ 1. N an animal tissue consisting of one or more layers of closely packed cells covering the external and internal surfaces of the body. The cells vary in structure according to their function, which may be protective, secretory, or absorptive 上皮 返回 epithelium劍橋詞典a layer of cells covering all the surfaces of the body except the interior of blood and lymph vessels 上皮，上皮組織 返回 epithelium