Bird, crop (LM, Low)

Structure List Lumen Epithelial layer Lamina propria Muscular layers

AVIAN CROP. The crop of birds is a modification of the esophagus used primarily for storage and softening of food. It has the same structural organization as the rest of the esophagus. The lining epithelium is stratified squamous. Unlike the rest of the esophagus, the lamina propria does not have mucous glands. There are three layers of smooth muscle in the wall. The muscularis mucosa is longitudinal. The internal layer of the muscularis externa is circular, and the outer layer of the muscularis externa is longitudinal.