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Mucosal membrane
A mucosa, lining the lumen of any hollow organ opening to the exterior, is the most variable of the three types of 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. Examples include simple columnar epithelium, simple cuboidal epithelium, pseudostratified epithelium, stratified squamous epithelium and transitional epithelium.

Glands >
The tubes extending through lamina propria are glands, consisting of a 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 watery gel, this layer provides good cushioning for its covering epithelium, padding for any glands present, diffusion of nutrients and migration of cells.

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