the epithelium of the small intestine is what and the finger folds are called
1 large circular folds called plicae circulares (shown in the diagram to the right), most numerous in the upper part of the small intestine. 2  smaller folds called villi, which are finger like mucosal projections, about 1mm long.o aid in digestion and absorption: 1  the small intestine secretes enzymes and has mucous producing glands. 2  The pancreas and liver also deliver their exocrine secretions into the duodenum. 3  The mucosa is highly folded.