Crypt depth and proliferation status in rats fed the experimental diets (low fibre control diet (CD), starch free wheat bran enriched diet (WB), type III resistant starch enriched diet (RS), and short chain fructo-oligosaccharide enriched diet (FOS)) for 44 days (median (min–max))
| CD | WB | RS | FOS | |
| Crypt depth (μm) | ||||
| Caecum | 143 (125–150) | 144 (135–180) | 162 (154–177) | 162 (149–174) |
| Colon | 282 (221–297) | 324 (231–350) | 295 (234–303) | 264 (221–277) |
| Rectum | 191 (184–213) | 224 (191–252) | 221 (211–289) | 215 (204–225) |
| Count of PCNA+ cells relative to crypt depth | ||||
| Caecum | 0.91 (0.72–1.41) | 0.95 (0.68–1.97) | 0.82 (0.78–1.05) | 0.90 (0.62–1.23) |
| Colon | 1.42 (1.06–2.51) | 1.33 (0.78–2.53) | 2.10 (1.54–2.83) | 1.88 (1.88–1.98) |
| Rectum | 3.56 (3.50–3.61) | 2.15 (1.12–5.68) | 1.81 (0.35–2.82) | 3.12 (3.05–3.62) |
| Height of the proliferative zone (% crypt depth) | ||||
| Caecum | 36 (30–52) | 36 (25–47) | 36 (26–54) | 37 (25–46) |
| Colon | 40 (29–47) | 33 (31–49) | 45 (39–52) | 41 (30–44) |
| Rectum | 31 (30–31) | 26 (16–39) | 25 (21–29) | 28 (26–35) |
For each rat (n=16, four blocks), samples labelled with antiproliferating cell nuclear antigen (PCNA) were issued from the caecum (caecal apex), colon (upper part of the distal colon), and rectum (end of the distal colon). Only crypts with a lumen visible from bottom to top were taken into account, and 30–50 crypts per large intestine segment were analysed. All observations were performed blind. The measurements were the depth of the crypt (upper limit: just under the surface epithelium), the number of PCNA positive cells per crypt, and the height of the proliferative zone (upper limit: top of the highest labelled cell). Two proliferation indexes were constructed: ratio of positive cells to crypt depth, and height of the proliferative zone relative to crypt depth. For each rat, the mean values for observed crypts were determined per segment.
Analyses of the effect of diet were performed independently for the caecum, colon, and rectum. Ranked data were analysed using the ANOVA model: Y=diet+block, followed by Bonferroni's test. In the caecum, crypts were deeper with RS (p =0.048) and FOS (p =0.078, NS) than with CD. No proliferation index was statistically different between fibre enriched diets and CD. The proliferative zone was always limited to the lowest 60% of crypts (maximum height 54%).