Fig. 5. PCNA and TUNEL labelling of colonic crypts. (A-D) PCNA staining of Igf2 knockout (A), wild type (B), K:Igf2 samples (C) and. negative control (D; wild-type sample with primary antibody omitted). The proportion of the crypt that is PCNA positive is greater in the K:Igf2. The knockout crypt shown is quite short but within the normal range of sizes. Scale bars: 25 µm. Arrowheads indicate the upper limit of PCNA-positive cells. (E,F) Crypt from a wild-type animal viewed for TUNEL (E; showing a single apoptotic cell) and DAPI (F, showing all nuclei) staining. Scale bars: 50 µm.