submucossa

Submucosa, known in Portuguese as submucossa, is a layer of the wall of the gastrointestinal tract and other tubular organs located between the mucosa and the muscularis externa. It consists of loose to dense irregular connective tissue and contains blood vessels, lymphatics, and nerve fibers. The submucosa houses the submucosal nerve plexus, commonly referred to as Meissner's plexus, which regulates vascular tone and glandular activity, and coordinates with the muscularis mucosae.

Within the submucosa are various structures depending on the region. In the duodenum and some other regions, Brunner's glands reside in the submucosa and secrete bicarbonate-rich mucus. In the esophagus, submucosal glands may provide mucus. The layer also provides a supportive scaffold for the mucosa and serves as a conduit for vessels and nerves supplying the mucosa and mucosal glands.

Functionally, the submucosa serves to stabilize the mucosa, support its vascular and neural networks, and facilitate coordinated secretion and local blood flow. It enables the passage of nutrients, immune cells, and signaling molecules between the mucosa and deeper layers of the wall.

Clinical relevance: The submucosa is a target for certain endoscopic procedures, including submucosal injection to lift lesions prior to resection. Submucosal tumors originate in this layer and can be assessed with imaging and endoscopic ultrasound.