A simple epithelium has only one layer of cells.

一个简单的上皮只有一层细胞。

The endometrium is itself made up of a single layer of simple columnar epithelium, which has ciliated and secretory cells, that sit on top of connective tissue, or stroma.

子宫内膜由单层柱状上皮构成；单层柱状上皮有纤毛细胞及分泌细胞，位于结缔组织即基质顶部。