Analysis of epithelial maturation and transit in the small intestines of En/Erm low-expressor mice (Tg
) and non-transgenic controls (Tg
). Transgenic animals show appropriate loss of nuclear Mcm6 expression along the crypt-villus axis, indistinguishable from controls, reflecting normal epithelial maturation. In contrast, crypt-villus epithelial transit, as determined by in vivo BrdU labeling , is increased in transgenic animals compared to controls (top solid line: villus tips; bottom solid line: crypt-villus junction; dashed line: overall upper limit of epithelial transit; arrowheads: upper limit of epithelial transit in individual villi). Representative images of mid small intestine are shown for both groups.