
Mucous membrane
A mucosa, lining the lumen of any hollow organ opening to the exterior, is the most variable of the three membranes. It typically consists of an epithelium, a connective tissue lamina propria, and a muscularis mucosae of smooth muscle. A mucous membrane is so named because mucus-producing glands frequently secrete onto its surface, providing lubrication. 400x

Epithelium >
The epithelium of a mucous membrane varies greatly depending on the location and function of the organ: simple columnar epithelium, simple cuboidal epithelium, pseudostratified epithelium, stratified squamous epithelium, or transitional epithelium.

Glands >
The tubes extending through lamina propria are glands, secretory epithelium, whose secretions lubricate the surface of this organ.

Lamina propria >
The lamina propria of a mucosa is loose connective tissue. Because the ground substance of loose connective tissue is a gel, this layer provides good cushioning for its covering epithelium, padding for any glands present and diffusion of nutrients.

Muscularis mucosae >
The muscularis mucosae of a mucous membrane is smooth muscle. This layer may be incomplete or lacking in some organs.