Quantitative immunohistochemical and flow cytometric analyses of conventionally raised and germ-free FVB/N Fabpi-TAg(Wt), Fabpi-TAg(K107/8), and nontransgenic mice disclosed that forced reentry of enterocytes into the cell cycle is accompanied by an influx of thymically educated alphabeta T cell receptor (TCR)(+) CD4(+) and alphabeta TCR(+) CD8alphabeta(+) IELs and a decrease in intestinally derived gammadelta TCR(+) CD8alphaalpha IELs.