Abstract
The aim of this study was to investigate the cell kinetics and epithelial structure in the intestinal tract in cohorts of young and old germfree (GF) and conventional AGUS rats of both sexes. The young rats were 35 days old and the old rats were 190960 days old. All rats were fed the same diet and water ad libitum. At the beginning of the experiments, the rats were starved for 2.5 h. Thereafter, all animals were given vincristine 1 mg/kg intraperitoneally (i.p.) 4 h before they were sacrificed. Specimens from eight parts of the intestine were investigated. The cell kinetic parameters determined in the small intestine were percentage of cells in mitosis, growth fraction (GrF), total number of cells in the crypts and villi, depth of the crypts, height of villi and the crypt/villus (C/V) ratio. In the colon, the percentage of cells in mitosis, GrF and the total number of cells in the crypts, as well as depth of the crypts, were determined. Taken together, the effect of gender was most pronounced in the upper part of the small intestine, the effect of age was most pronounced in the lower small intestine, whereas the effect of microbial status was relatively more pronounced in the duodenum and in the large intestine. Thus, these factors are acting in a compartmentalized manner in the intestinal tract. In conclusion, gender, age and microbial status have to be taken