The middle layer is the lamina propria and it contains blood and lymph vessels.

粘膜层的中层为固有层，内含血管和淋巴管。

The mucosa also has three layers of its own: a layer made of stratified squamous epithelium; a layer of connective tissue, called the lamina propria; and a layer of muscle cells, called the muscularis mucosae.

黏膜层本身又由三层结构组成，一层复层鳞状上皮，一层结缔组织，又叫固有层，还有一层肌细胞，又叫黏膜肌层。