MORPHOLOGICAL-CHARACTERISTICS, EPITHELIAL-CELL PROLIFERATION, AND CRYPT FISSION IN CECUM AND COLON OF GROWING PIGS

Morphological characteristics and cellular proliferation were investig ated in the hindgut tissue of 25 pigs ranging from 5 to 261 days of ag e; the three youngest pigs were unweaned. Tissue samples were taken fr om the cecum and from the proximal, middle, and distal part of the col on. 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 sulfom ucins. Distinct regional differences were observed between the four in testinal sites. In general, the crypts were deeper and more closely sp aced and the turnover time was higher in the distal part of the colon as compared to the cecum and the proximal colon. Furthermore, a greate r 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 i n morphological characteristics of the hindgut in pigs may have signif icance for the etiology of intestinal infections.