The mammalian digestive tract ileum is the final section of the small intestine. The first and second section of the small intestine respectively are the duodenum and the jejunum.

The duodenum is where proteins and lipids get broken down with the aid of liver bile and stomach chyme, while the ileum is where bile acids and vitamin B12 get absorbed.

The microstructure of the ileum reveals many adaptations for its function. Firstly, it has multiple layers. The outermost layer is the serosa which serves to lubricate the outside of organs by secreting serous fluid. This prevents friction and inflammation, in addition to supporting the…