Cell surface components of intestinal epithelial cells and their relationship to cellular differentiation

The surfaces of the epithelial cells of the rat small intestine were studied by fluorescence microscopy using various fluorescein isothiocyanate-conjugated lectins. Throughout most of the adult intestine changes were detected in the luminal surfaces as the cells differentiate and move from the crypts to the villi. These changes in cell surface material depend upon the region of intestine in which the villi are located. By the end of the second week of postnatal development the cell surface components detected by the lectins used in this study have appeared at all levels of the small intestine. The maturational and regional differences begin to appear during the third week of postnatal development, and the adult pattern of distribution of surface components is established by 30 days after birth. By eight weeks after proximal jejunal-ileal resectioning or transposition of ileal segments to the jejunum, the epithelial cell surfaces of the relocated ileum had acquired the surface properties characteristic of the jejunal cells. However, jejunal segments transposed to the ileum maintained their original cell surface characteristics and influenced the properties of ileal cell surfaces distally adjacent to the transposed segment. The cell surface material detected by the Ricinus communis (RCAI) lectin was extracted from crypt cells of adult rat jejunum and isolated by affinity chromatography. The isolated material was found to contain at least two components, and its distribution in the jejunum was examined by fluorescence microscopy using antibodies prepared against the isolated material.