Immunohistochemistry Calbindin-D9k. Immunohistochemistry was performed to localise calbindin-D9k expression in the intestinal wall. The strongest labelling was visible in the villi of the duodenum (DD) followed by that of the jejunum (JE). Considerably weaker staining was observed in the cecum (CC) and in the colon ascendens ventrale (CAV). Inside the enterocytes, the strongest staining was seen in the cytoplasm.