Histology, Histochemistry and scanning electron microscopy of stomach of goat (Capra hircus)

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Date
2008
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LUVAS
Abstract
The present work was conducted on stomach of ten young goats, aged 6-9 months. The forestomach wall of goat was lined throughout with stratified squamous keratinized epithelium having strata corneum, granulosum, spinosum and basale. Iron granules were present in the superficial most layer of stratum corneum in the forestomach. Submucosa was consisted of loose connective tissue fibres, predominantly of collagen with a few elastic and reticular fibres. In all types of papillae of forestomach the connective tissue core made protrusions called papillary bodies inbetween the stratified squamous cell layers. The tunica muscularis comprised of well developed inner circular and outer longitudinal layers of smooth muscle throughout the forestomach. The tunica serosa of the forestomach comprised of an outer flat mesothelial cell layer and an inner loose irregular connective tissue having fine blood capillaries and fatty tissue. In rumen, the papillae varied in size and shape from tongue shaped to conical or leaf like. The lamina propria mucosae blended with the submucosa forming propria submucosa due to the absence of lamina muscularis mucosae. The epithelial mucosa of reticulum was folded to form the primary fold which along with the adjacent mucosa had secondary and tertiary papillae. The lamina muscularis mucosae extended towards the tip of the papillae in the primary folds whereas in secondary crests and tertiary papillae, the lamina propria mucosae merged with the submucosa. The omasum had large and small laminae of 5 distinct orders. The I and II order had the papillae whereas III order laminae possessed only few papillae and in IV order it was absent. Lamina propria mucosae extended into the core of I, II, III and IV order laminae. It was very less extended in the V type of papillae. The lamina propria mucosae was thinner and less developed than that of the rumen and reticulum. It was externally bounded by a prominent lamina muscularis mucosae that extended into each omasal fold. The inner circular layer of tunica muscularis of omasum continued into the omasal laminae (I, II and III) as their central muscle layer into the laminae to form its central sheet. Unguliform papillae were present in the reticulo-omasal junction and lip of omasal groove. The abomasum showed the cardiac, fundic and pyloric regions. In the fundic region all the four cell types i.e. mucous neck cells, parietal cells, chief cells and enterochromaffin cells were observed. Histochemically, neutral mucopolysaccharides predominated towards the gastric areas whereas towards the pits a mixed distribution of acidic and neutral mucopolysaccharides were observed. Alcianophilic and PAS reaction was very strong in the surface epithelial cells. The scanning electron microscopic studies supported the histological findings in the stomach of goat. SEM revealed large leaf like papillae to tongue shaped, pointed and blunt forms of papillae in rumen. At the ruminoreticular junction the papillae were thin, narrow and pointed with sharp edges. Both the longitudinal and ventral coronary pillars showed folded mucosa with large and small papillae. SEM showed that the reticular cells were separated from each other by primary fold, had secondary folds where smooth surfaced papillae were present. At reticulo-omasal junction large unguliform and conical papillae were present. SEM of omasum revealed 5 distinct order of laminae and three types of papillae in each laminae. The type- I and type- II smooth surface papillae were conical or triangular and comparatively larger than the type- III papillae. The unguliform papillae were trifid, the central division being largest. The omaso-abomasal junction, was separated by a small groove and a cord like fold of mucosa. SEM of fundic gland region showed the cells of irregular shapes and dimensions with their raised borders. Different structures were observed towards the centre of these cells, on the basis of which the cells were categorized into different types. The pyloric region also had the clusters of 2 types of cells which were separated from each other by their lateral walls. SEM of torus pyloricus revealed small raised or elevated areas, which further comprised of small globular structures having small microvilli and folds of mucous membrane. Abomaso-duodenal junction was revealed by SEM. The duodenal portion was characterized by presence of a meshwork of small cilia like structure and this portion also showed two types of cells
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