Background: 1. During maturation of the infant, the ratio of intestinal villi/crypt (V/C) length/depth decreases. 2. The age at transition from infancy (weaning) determines human and rat growth trajectories (Crispel, BMC Med, 2013).
Objective: To examine the impact of weaning age on the morphological changes that occur in rat`s intestine.
Materials and Methods: We investigated intestinal morphology and morphometrics and measured length and body mass index (BMI) at age 21days (weaning age) and 90 days (adult) in pups weaned early (d16), normally (d21) or late (d26). Seven sites along the small intestines were examined microscopically with software that enables metrics and histology of the intestine.
Results: Rats who weaned early (d16) were longer (mean length 45 cm) and thinner (mean BMI 0.21 g/cm2) than d21 (42cm, 0.25 g/cm2) and d26 group (41cm, 0.26 g/cm2; p<0.001). At age 21d the d16 weaned rats had lower V/C ratio (2.4±0.1) as compared to rats that suckle until d21(3.2±0.3, p = 0.003). As they became adult, at d90 the V/C ratio was 3.9±0.6 in the d16 weaned rats, as compared to 2.9±0.2 for d21(p=0.01) and 3.1±0.2 for d26 weaned rats (p<0.05). On d90, the d16 rats villous thickness was greater (105±7 µm) versus 91±6 µm in d21 (p<0.05) and 89±6 µm in d26 rats (p<0.05).
Conclusions: Early weaning results in long thin rats and early maturation of the intestine, as evident from the lower V/C ratio. As these animals become adults, the early weaned would have better intestinal morphology: greater V/C ratio and thicker villi.
