Abstract
In spite of the widespread use of rats in gastrointestinal research, there is a lack of information on the qualitative and quantitative histological characteristics. Therefore, a study was performed in 69 male Wistar rats with ages ranging from one day to one year old. The features studied included: height and number of villi in the duodenum, jejunum and ileum, and depth and number of crypts in the duodenum, jejunum, ileum, colon and rectum. Morphometric observations were expressed in a mathematical logarithmic curve that showed a normal pattern of intestinal growth for each intestinal level. The number of villi in the small intestine decreased from 1 to 35 days of age, whereas the other intestinal parameters all increased during the same period. After 35 days the rates of increase or decrease were lower. The quantification of these intestinal changes provides a new complementary pattern as a reference for research as indicators of normality or malfunction in the rat intestine.