
Overview: serosa
Most of the small intestine protrudes into an internal body cavity (peritoneal) and is, therefore, covered by a serosa: a connective tissue layer and its overlying simple squamous epithelium (mesothelium). A portion of the duodenum is retroperitoneal and is surrounded only by a connective tissue layer, the adventitia where it contacts the posterior body wall. (For a more detailed review of these two layers, see the General Concepts: Membranes.) 800x

Serosa
Most of the small intestine protrudes into an internal body cavity (peritoneal) and is, therefore, covered by a serosa: a connective tissue layer and its overlying simple squamous epithelium (mesothelium). A portion of the duodenum is retroperitoneal and is surrounded only by a connective tissue layer, the adventitia where it contacts the posterior body wall. (For a more detailed review of these two layers, see the General Concepts: Membranes.) 800x

- Connective tissue
Most of the small intestine protrudes into an internal body cavity (peritoneal) and is, therefore, covered by a serosa: a connective tissue layer and its overlying simple squamous epithelium (mesothelium). A portion of the duodenum is retroperitoneal and is surrounded only by a connective tissue layer, the adventitia where it contacts the posterior body wall. (For a more detailed review of these two layers, see the General Concepts: Membranes.) 800x

- Mesothelium
Most of the small intestine protrudes into an internal body cavity (peritoneal) and is, therefore, covered by a serosa: a connective tissue layer and its overlying simple squamous epithelium (mesothelium). A portion of the duodenum is retroperitoneal and is surrounded only by a connective tissue layer, the adventitia where it contacts the posterior body wall. (For a more detailed review of these two layers, see the General Concepts: Membranes.) 800x

Blood vessels
Most of the small intestine protrudes into an internal body cavity (peritoneal) and is, therefore, covered by a serosa: a connective tissue layer and its overlying simple squamous epithelium (mesothelium). A portion of the duodenum is retroperitoneal and is surrounded only by a connective tissue layer, the adventitia where it contacts the posterior body wall. (For a more detailed review of these two layers, see the General Concepts: Membranes.) 800x

Muscularis externa
Most of the small intestine protrudes into an internal body cavity (peritoneal) and is, therefore, covered by a serosa: a connective tissue layer and its overlying simple squamous epithelium (mesothelium). A portion of the duodenum is retroperitoneal and is surrounded only by a connective tissue layer, the adventitia where it contacts the posterior body wall. (For a more detailed review of these two layers, see the General Concepts: Membranes.) 800x