上皮形成

例句：

1. 1.Epithelial cells are responsible for the formation of the skin's outer layer.
   上皮细胞负责形成皮肤外层。
2. 2.The epithelial lining of the stomach protects it from harmful substances.
   胃的上皮层保护胃免受有害物质侵害。
3. 3. In the development of new drugs, scientists often study the behavior of epithelial cells.
   在开发新药物的过程中，科学家们经常研究上皮细胞的行为。