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Background:This work was performed to study the different parts of gastrointestinal tract mucosa in adult albino rats with concentration on the goblet and enteroendocrine cellsMaterial and methodsFifteen adult male albino rats of three to six months old age were used, the animals were anaesthetized with ethyl ether, labarotomy was done and the gastrointestinal tract of the rat was divided into eight portions according to general classification of mammalian GIT. Samples from fundus, pylorus, duodenum, jejunum, ileum and colon were taken, each of which was 1 cm long and were fixed in 10 % buffered formalin and processed for paraffin sections which were stained with H&E, Alcian blue and immunohistochemical stain for chromogranin A; a marker of enteroendocrine cells and examined with light microscope. The mean value of area% of CgA immunoreactive cells were calculated by the help of image analysis and compared with each others for the sex segments to be studied.Samples from pylorus, duodenum and colon removed from animal and were placed on a dental wax in a drop of the primary fixative and cut them with sharp razor into minute small pieces (1 mm) and fixed immediately in a buffered gluteraldehyde solution at PH (7.4) from 2 to 24 hours in a refrigerator at 4°C then processed for transmission electron microscope examination.Results :The mucosa of the fundus consisted of surface epithelium that invaginated to varying extent into the lamina propria forming narrow gastric pits, emptying into the gastric pits were branched tubular glands compared to wide pits of the, highly coiled glands of the pylorus with scattered clear cells with vesicular nuclei in both.The villus shape was broad leaf like in the duodenum, tongue shaped in jejunum, slender finger like in ileum with decreased number from duodenum to ileum, no villi detected in the colon. There was mucous Brunner’s glands in submucosa of duodenum, Peyer’s patches in submucosa of ileum and nothing detected in submucosa of jejunum.The goblet cells number were less in duodenum increasing downward toward the colon where they show higher frequency as shown with alcian blue stain specific for acidic mucin presents in goblet cells.Immunohistochemical study for detection of enteroendocrine cells Showed that CgA immunoreactive cells were observed throughout the gastrointestinal tract and they showed highest frequencies in the pylorus and duodenum, and they were more basal.The results of electron microscopic examination revealed presence of mucous secreting columnar cell, parietal cell and chief cell in the fundus, columnar absorptive cell and goblet cell in the duodenum and presence of columnar absorptive cell, goblet cell and enteroendocrine cell in the colon.Conclusion:It is concluded that there were differences between the segments of the gastrointestinal tract mucosa in shape and distribution of cells along the gastrointestinal tract going with the function done by each part
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