The relationship between the functional and structural alterations in the rat small intestine following proximal resection of varying extents.

The functional and structural characteristics of the ileal remnant of rat intestine were examined four weeks after 45%, 70% or 95% proximal resection. The increase in villus height in the ileal remnant had alfread reached its maximum after a resection of 45%, whereas a further increment in the length of the crypts occurred after 70% resection. There was an increase in the number of enterocytes per unit length of villus and a rise in the DNA content per unit weight of mucosal scrapings, which testifies to the development of mucosal hyperplasia in this situation. The specific activities of sucrase, measured biochemically, and of nonspecific esterase, determined histochemically, were reduced in proportion to the extent of the resection. Similarly, the uptakes of L-phenylalanine and of beta-methyl-D-glucoside by intestinal rings in vitro were progressively diminished in the ileal remnant. There was an increase in the rate of disappearance of glucose from a perfused loop in vivo, when expressed in terms of unit intestinal length. Galactose absorption remained unchanged, but when expressed in terms of unit dry tissue, was significantly reduced, in agreement with the diminished transport of both amino-acids and monosaccharides in vitro.