The epithelial "membrane" of the small intestine.
D002838:Chromaffin System; D004847:Epithelial Cells; D004848:Epithelium / Q000033:anatomy & histology; D006801:Humans; D007413:Intestinal Mucosa; D007421:Intestine, Small / Q000033:anatomy & histology* / Q000166:cytology; D008566:Membranes / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology