A quantitative morphometric analysis of rat ileal Thiry-Vella fistulae

Controversy exists regarding the mechanism and degree of mucosal alterations occurring in defunctionalized segments of intestine. This study compares the results of a quantitative analysis of mucosal components, including Paneth cells and immunocytes, between in-continuity and defunctionalized (Thiry-Vella) segments of rat ileum. The micrometer component quantitator was used for the light microscopic morphometric analysis. Intracellular lysozyme and IgA were identified employing the unlabeled antibody enzyme immunohistochemical staining technique. The vol% of the ileal mucosal components of animals from the control group and from the in-continuity segments of the experimental group were comparable. Analysis of the Thiry-Vella fistulae, however, revealed a statistically significant decrease in the vol% of columnar epithelial cells and increase in the vol% of lysozyme-containing Paneth cells and interstitium of the lamina propria. Since Thiry-Vella fistulae are neurovascularly intact, mucosal alterations imply a causal relationship to interaction with chyme. The data suggest that chyme has both a stimulatory (on the columnar epithelium) and suppressive (on the the Paneth cell population) effect. The vol% of IgA-containing Paneth cells and the percentage of the lamina propria represented by IgA-containing immunocytes were also substantially decreased. Normally secretory IgA is the immunoglobulin of highest concentration intraluminally and among immunocytes within the lamina propria, presumably in response to local antigenic stimulation. The presence of immunoglobulin within Paneth cells may reflect the phagocytosis of immunoglobulin complexed antigens. The data suggest that the degree of local antigenic stimulation is decreased in Thiry-Vella fistulae.