Abstract
The mucosal surface area of the guinea pig duodenum, jejunum, and ileum was determined during development, in three age groups: 1โdayโold and 2โ and 12โweekโold animals. The morphometric analysis was performed at three magnification levels. The nominal surface area was determined at the macroscopic level, from intestinal length and perimeter. Villus and microvillus amplification factors were estimated at lightโmicroscopic and transmission electronโmicroscopic levels, respectively. We found: (1) an increase in the nominal surface area that is maximal in the ileum (7.7โfold); (2) an increase in the villus amplification factor in the duodenum (1.4โfold) and a decline in the jejunum and ileum (0.8โfold), although in the jejunum villus dimensions rise; and (3) a similar increase in the microvillus amplification factor in the three segments (1.1โ to 1.4โfold). In conclusion, the total mucosal surface area increased from day 1 to week 12, by 3โfold in the duodenum and jejunum and by 8โfold in the ileum. Regionally, the jejunum shows the largest mucosal surface area, followed by the ileum, and, finally, the duodenum. Microsc. Res. Tech. 63:206โ214, 2004. ยฉ 2004 WileyโLiss, Inc.