哺乳动物肺泡上皮主要由肺泡Ⅱ型上皮细胞 (typeⅡalveolarepithelialcell,AECⅡ )和Ⅰ型细胞 (AECⅠ )构成。AECⅡ胞体较小 ,圆形或立方形 ,散在嵌于Ⅰ型细胞之间 ,细胞数量较Ⅰ型细胞多 ,但仅覆盖肺泡表面的一小部分。AECⅡ是一种分泌细胞 ,光镜观察下 ,核圆形 ,胞质着色浅 , Mammal alveolar epithelium mainly consists of type II alveolar epithelial cells (AECII) and type I cells (AECI). AECII small, round or cubic cells scattered in type I cells interspersed with more cells than type I cells, but only cover a small part of the alveolar surface. AEC Ⅱ is a secreting cell, light microscopy, nuclear round, pale cytoplasm,