Cytochemical analysis of single villus peptidase activities in pig intestine during neonatal development

The present work uses a new technique of whole tissue cytochemistry and automated scanning to obtain measurements of peptidase activity and surface structure in intact villi microdissected from the jejunum of newborn and 28-day-old pigs. Intact villi from 28-day-old pigs are shown by this method to contain 30% more aminopeptidase N and 400% more dipeptidylpeptidase IV activity than is found on villi taken from newborn pig intestine. Villi taken from 28-day-old pig intestine are also half as long and twice as wide at their base as those taken from newborn animals. These changes in shape take place without significantly affecting the total surface area of the villus. Increases in peptidase activities occurring during postnatal development can be further subdivided into those dependent upon induced changes in enterocyte biochemistry and those dependent upon the changing geometry of villi. Over 90% of the total increase in peptidase activities occurring during neonatal development was shown, by this analysis, to involve enterocyte reprogramming of enzyme production. The present method of whole tissue cytochemistry appears to combine successfully the ability to measure peptidase activities at the cellular level in undisrupted tissue with a facility to relate these results to the overall shape of a single villus. These and more general applications of the method now provide new ways to analyse a variety of changes taking place in intestinal structure and function in a quantitative manner.