Fig. 7. Wax sections of normal human colonic epithelium stained using immunocytochemistry for prolyl-4-hydroxylase. (A) Positive staining is seen in both epithelial cells (wide arrows) and pericryptal mesenchymal cells (thin arrow). (B) Fluorescence microscopy of the same section shows that autofluorescence of endocrine cells colocalises with the epithelial prolyl-4-hydroxylase staining. Bar, 50 µm.