Abstract
Biochemical studies on proliferation and maturation of rat fundic and jejunal epithelial cells were performed. By using frozen horizontal sectioning technique to mucosal epithelial cells of fundus and jejunum, correlation between cell proliferation and maturation were studied. The incorporation of TdR-14C into acid-insoluble fraction was measured as a marker of cell proliferation and the development of activities of specified enzymes of those tissues were assayed as markers of maturation.
Studies on incorporation of TdR-14C with rat fundus revealed that radioactivity of TdR-14C was quickly incorporated into lower part of surface epithelium and mucous neck zone. Radioactivity which was incorporated into proliferative zone migrated to the top of surface epithelium about 65 hours after the injection. About 180 hours after the injection, however almost all the radioactivity shed from mucous membrane of fundus, radioactivity remained slightly on the mucous neck zone and deeper part of fundic glands. Two directions of migration of fundic epithelial cells were suggested. One was upward direction from the proliferative zone. Cells migrated up and shed from the surface epithelium during short period. The other was downward direction from the proliferative zone. Cells migrated down very slowly or stayed for a while at proliferative zone.
Enzymatic studies with fundus showed that zone with the activities of specified enzymes coincided with the histological distribution of marker cells. Zone with activity of fucosyltransferase coincided with the distribution of mucous producing cells, zone with pepsinogen with chief cells and zone with Mg++-HCO-3 ATPase with parietal cells.
Studies on incorporation of TdR-14C with jejunum revealed that radioactivity was quickly incorporated into crypts zone. The radioactivity migrated up along villi and shedfrom the tip of villi about 48 hours after the injection.
Enzymatic studies with jejunum showed that sucrase and alkaline-phosphatase activities were low in crypts and greatly increased along the villi from crypts to tips.
Studies on incorporation of TdR-14C and enzymatic studies suggested gastiointestinal cells matured during migration.
