Scanning Electron Microscopic Study of Caprine Intestine with Special Reference to Gut-Associated Lymphoid Tissues

Abstract

The intestine of adult indigenous goat of Assam (Capra hircus) was studied by scanning electron microscopy (SEM) for elucidating the morphology of intestinal mucosa as well as the morphology of gutassociated lymphoid tissue including Peyer's patches (PP) and solitary lymphoid nodule. SEM of intestines revealed the presence of villi in the small intestinal mucosa. Goblet cells were noticed as white pinheads on the villus surface between the enterocytes. The large intestinal mucosa of adult Assam local goat was devoid of villi. SEM of small intestinal mucosa revealed leaf or finger-like absorptive villi covering PP. Even the dome villi were completely covered by absorptive villi and were shorter than the absorptive villi. The absorptive villi in all segments of the small intestine had numerous microvilli. The interfollicular region had high endothelial venules. Propria nodules were lymphoid nodules predominantly in lamina propria and covered by distinct follicle-associated epithelium which lacked goblet cells and openings to deep invaginations into the mucosa.Keywords: Goat, gut-associated lymphoid tissue, intestine, scanning electron microscopy, villi.SCANNING electron microscopic studies on intestinal mucosa and gut-associated lymphoid tissue (GALT) have been conducted by several researchers like Mebus et al. 1 in gnotobiotic calf; Cormack 2 in human and mouse; Wile and Nakov 3 in horse; Wile 4 in ox, sheep and goat. However, such studies on the intestine and GALT of goat are meagre. In the present study, intestine of adult indigenous goat of Assam (Capra hircus) was studied by scanning electron microscopy (SEM) for elucidating the morphological characteristics of intestinal mucosa and GALT including the Peyer's patches (PP) and the solitary lymphoid nodule (SLN). The study, therefore, would contribute to further research on the GALT of herbivores.The intestines were procured from local slaughter houses after careful observation of the slaughtered animals. Representative tissue samples were collected from all segments of small and large intestines. From each segment, samples were obtained from cranial, middle and caudal parts. The samples were preserved in 2% glutaraldehyde solution in 0.1 M cacodylate buffer and processed for SEM 5 and were examined in JMS-35(CF) Joel scanning electron microscope operated at 20 kV at the Sophisticated Analytical Instrument Facility, North Eastern Hill University (NEHU), Shillong, India.The SEM of intestines of adult goat revealed the presence of villi in the small intestinal mucosal surface. The villi were mostly finger-like with variable size and shape depending upon area. The duodenal villi, especially in the proximal part were mostly leaf-like and broader, whereas the villi of distal duodenum, jejunum and ileum were finger-like, longer and slender (Figures 1 and 2). Microvilli were seen on the villus surface and the cores of villi were made up of lamina propria (Figure 3). Similar observations were reported by Cormack 2 in human small intestine where variations in villi...