Bird, crop (LM, Low)

Structure List Lumen Epithelial layer Lamina propria Muscular layers

EPITHELIAL CELL LAYER - this layer, in contact with and lining the lumen of the digestive tract, is composed of epithelial cells whose morphology and function vary along the course of the tract. The epithelium may be composed of STRATIFIED SQUAMOUS epithelial cells in regions where the tract functions mainly in transport of ingesta (e.g., esophagus); or it may be composed of SECRETORY CELLS (e.g., in portions of the stomach); or ABSORPTIVE CELLS (e.g., duodenum), or both.