Localization and Morphology of Serotonin Cells in Intestinal Gland of Rodents

Lee, Byoung Seung; Lee, Jung Eun; Cha, Jung Ho

Abstract

This study was an attempt to investigate the relative distribution and morphology of serotonin cells (SC) in intestinal glands of adult rodents, rats, guinea pigs and mice. The intact isolated epithelial sheets of intestinal glands from duodenum, jejunum, ileum, cecum, and proximal and distal colon were prepared for immunohistochemistry using antiserotonin antisera. Examination of isolated epithelia reveals an actual number of SC in one intestinal gland and whole image of individual serotonin cell. In small intestine of all species in this study, the average number of SC per one intestinal gland was the highest in duodenum, and decreased in jejunum and ileum. The distributional patterns of SC in large intestine of three species, however, were different. The number of SC decreased towards distal colon in both rat and guinea pig, and vice versa in mouse. And in the rat, the number of SC in colon was even higher than in duodenum, while in the guinea pig the number of SC in colon was lower than any other part of small intestine. In all the intestinal region of three species, SC were more numerous towards the bases of glands. The open type of SC whose apical cytoplasmic process reach glandular lumen were predominant (over 97% in average) in small intestine of all species in this study. The frequency of closed type was increased in large intestine (up to 44.9% in proximal colon of guinea pig). And closed type was more frequently detected towards the upper part of gland. In small intestine of all species in this study, SC were predominantly flask-like in shape without basal processes. In large intestine, SC with basal processes were often detected, and their frequencies increased towards the upper part of gland. In mice, basal processes were usually long in length (over the long axis of cell), while all the basal precesses of SC of guinea pig were short. We found that the isolated epithelium were very useful to figure out the actual number and whole images of enteroendocrine cells in intestinal mucosal epithelium. The present results demonstrated that relative distribution and morphology of SC were very different among the species especially in large intestine.