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.
This is because the muscle tissue has a greater blood supply than the area just under the skin. Muscle tissue may also hold a larger volume of medication than subcutaneous tissue. Intramuscular injection may be used instead of intravenous injection because some drugs are irritating to veins.) The site selected for injection is cleaned with an alcohol swab. The skin is allowed to air dry. 3) The practitioner spreads out the skin of the selected site to isolate the muscle. 4) The needle is inserted into the muscle at about a 90 degree angle.