The mucosal layer includes the epithelial layer, the intrinsic layer, the submucosal layer, and the connection between the mucosa and the underlying connective tissue called the basement membrane, as follows: 1. Epithelial layer: The epithelial layer mainly includes keratin-forming cells and non-keratin-forming cells, and the keratin-forming cells are divided into four layers, including the basal cell layer, the spiny cell layer, the granular layer, and the keratinized layer. 2. Non-keratin-forming cells are some cells scattered within the keratinocytes, including melanocytes, Langerhans cells, Merkel cells. 2, the lamina propria: the lamina propria is a relatively dense layer of the mucosa, a fibrous connective tissue, mainly to the epithelial layer to play a nutritional and supportive role. 3, the submucosa: the submucosa is a loose connective tissue, containing the glandular vessels, lymphatic vessels, nerves, fat tissue.