The mucosa of the small intestine is lined by a simple columnar epithelium which consists primarily of absorptive cells (enterocytes), with scattered goblet cells and occasional enteroendocrine cells.In crypts, the epithelium also includes Paneth cells and stem cells.he mucosa of the small intestine is characterized by evagination into plicae and villi, which increase the surface area for nutrient absorption, and by short tubular invaginations, the crypts, which provide a protected site for stem cells.
The following are sites where you can give a subcutaneous injection: 1  Abdomen: Uncover your abdomen. 2  Thigh: Uncover the entire leg. 3  Lower back: Uncover the back from the waist to the top of the buttocks.  Upper Arm: Uncover the arm to the shoulder.
Intramuscular (IM) injections are made into the striated muscle fibers that are under the subcutaneous layer of the skin. Thus needles used for the injections are generally 1 inch to 1.5 inches long and are generally 19 to 22 gauge in size.