Morphological characteristics, epithelial cell proliferation, and crypt fission in cecum and colon of growing pigs.

Morphological characteristics and cellular proliferation were investigated in the hindgut tissue of 25 pigs ranging from 5 to 261 days of age; the three youngest pigs were unweaned. Tissue samples were taken from the cecum and from the proximal, middle, and distal part of the colon. In the young pigs a high incidence of branched crypts was observed. During the first three to four months there was an increase in crypt height and proliferative activity, as determined by the mitotic count, as well as an increase in the mucin secretion, especially the sulfomucins. Distinct regional differences were observed between the four intestinal sites. In general, the crypts were deeper and more closely spaced and the turnover time was higher in the distal part of the colon as compared to the cecum and the proximal colon. Furthermore, a greater proportion of the mucins in the middle and distal part of the colon are acidic or sulfated as compared to the cecum, where the mucins are more of the neutral type. These regional and age-related differences in morphological characteristics of the hindgut in pigs may have significance for the etiology of intestinal infections.