FIG. 2.

Immunohistochemical localization of cryptdin 4 peptide in Paneth cells of distal mouse small intestine. Sections of adult mouse duodenum (A), jejunum (B through D), and ileum (E through G) were analyzed for the presence of the cryptdin 4 peptide, by using purified IgG from a polyclonal rabbit cryptdin 4-specific antibody (see Materials and Methods). In each panel, arrows indicate immunoperoxidase localization in Paneth cells of the crypts. Magnification, ×40. IgG prepared from preimmune serum is negative (H). Note that duodenal crypts are negative, jejunal crypts are modestly positive, and ileal crypts are strongly immunoreactive.