Villus height and crypt depth
The samples from the middle of duodenum, jejunum and ileum of small intestine of each segment were sectioned 6– 8 cm, flushed and kept in neutral buffered formalin solution until further morphometric analysis. The samples were then cut into two parts from each segment for cross and length section of intestine surface. Each segment was fixed in 10% formalin. Intestinal samples were excised and dehydrated for 16 h in a tissue processing machine (Leica ASP 3000, Japan) and then embedded in paraffin wax (Leica EG 1160, Japan). Each section was cut 4 μm thick (Leica RM 2155, Japan) and fixed on to the glass slides, heated at 57°C until samples were dried. The samples were stained with haematoxylin and eosin, mounted with coverslips. The villus height was measured as the distance between the crypt mouth and the tip of villi. The crypt depth was measured as the distance between the basement membrane and the mouth of crypt as using microscopes and read by PC Life Science Olympus software (Olympus Soft Imaging Solutions). This procedure was based on the method described by Bejo (1990).