1. 1. A technique is described for the fractionation of intestinal mucosal cells according to their position on the villous structures, followed by a separate procedure for the collection of the crypts. This provides a series of cell samples representing the complete migration process from the crypt to the apex of the villus. 2. 2. The validity of that part of the method which produces an exclusively crypt fraction has already been unequivocally demonstrated in a previous communication. The present paper examines the efficiency of the proposed technique for fractionation of the villous cells according to extent of migration. Radiothymidine-labelled gut cells proved to be a satisfactory test system for this purpose. The results were sufficiently satisfactory to warrant some surveys of chemical and enzymic changes during cell development. 3. 3. Cytochrome oxidase and glucose 6-phosphate dehydrogenase activities appear to remain at a constant level throughout cell development, whereas NADH-cytochrome c reductase shows a progressive increase from the time the cells leave the crypt zone. Invertase and alkaline phosphatase activities increase in a regular pattern with migration toward the villous tip reaching values which are respectively 31-fold and 60-fold that of the crypt. Esterase and leucine aminopeptidase show similar activity gradients. However, with the latter two enzymes, the maximal levels (at the top of the villus) are only 4-fold that of the crypt area. RNA content (on a protein basis) is highest in the crypt and in those cells at the base of the villus. The DNA/protein ratio is constant throughout all levels of the mucosal cells while showing a sharply-defined increase to double this concentration in the crypts. These results are discussed in relation to previously published work by other investigators. © 1969.
