Fig. 9. A single section of normal human colonic epithelium stained with in situ hybridisation for collagen IV mRNA (A) and immunocytochemistry for chromogranin A (B). A single crypt is shown to contain two collagen-IV mRNA-positive epithelial cells (short arrow) with an associated positively staining pericryptal fibroblast (long arrow) (A). Both collagen-IV mRNA-positive epithelial cells are shown to be chromogranin A positive (B). Bar, 25 µm.