The jejunum is the midsection of the small intestine, connecting the duodenum to the ileum. It is about 2.5 m long, and contains the plicae circulares, and villi that increase its surface area. Products of digestion (sugars, amino acids, and fatty acids) are absorbed into the bloodstream here.
Not to be confused with the cells of the islets of Langerhans, found in the pancreas, or Langhans giant cell.
Langerhans cells are monocytes within the epidermis that recognise and process small molecules penetrating the skin surface. These antigen-presenting cells are identified in tissue sections by characteristic surface markers. Pigment cells in the basal layer (melanocytes) protect the skin from ultraviolet radiation.