# Introduction he health of the digestive tract is important to receive the food material and for proper digestion and absorption. About 70 per cent of the body immune system is found in the digestive tract. This immune system often referred to as gut-associated lymphoid tissue and works to protect the body from invading pathogens (Ma et al., 2007). Peyer's patches are the aggregations of lymphatic nodules in the mucosa and submucosa of the jejunum and ileum of mice (Rowinski et al., 1984). Peyer's patches are immunocompetent lymphoid organs primarily engaged in immune responses to antigens presented from the intestinal lumen in guinea pig (Jurg et al., 1975). The secretions from the loops containing Peyer's patches exhibit a stronger early Ig A response to bacteria than the secretions from loops lacking Peyer's patches. The large number of lymphocytes in Peyer's patches increases the probability of an antigen encountering an immunocompetent cell (Keren et al., 1978). A thorough knowledge of the histological changes in gut-associated lymphoid tissue (GALT) is very essential to gain a comprehensive knowledge on the gut immunology and to form a basis for the interpretation of various pathological conditions of the gut. Hence, the present work has been undertaken to explore the histochemistry of the GALT in sheep. # II. # Materials And Methods Tissue pieces from the terminal part of jejunum and parts of ileum were collected from sheep. The tissues from six animals each from different age groups viz. three months, four months and five months in prenatal and neonatal (0-2 months), young (3-9 months) and adult (10 months-2 years) in postnatal groups were procured from the Corporation slaughter house, Perambur, Chennai. The determination of age ascertained as described by Richardson et al. (1976) in prenatal and Noden and de Lahunta (1985) in postnatal age groups. The routine paraffin sections of 3-5µm thickness were used for carbohydrates. Frozen sections of tissues fixed in chilled formol calcium (4ºC) were used for localization of alkaline phosphatase (Singh and Sulochana, 1996), acid phosphatase (Singh and Sulochana, 1996) and 5´Nucleotidase (Bancroft and Gamble, 2003). Frozen sections of fresh unfixed tissues were also used for localization of adenosine triphosphatase (Bancroft and Gamble, 2003). All the frozen sections were cut at 15-20µm thickness by cryostat. # III. # Results And Discussion # a) Carbohydrates The goblet cells of the villous epithelium were positive for PAS reaction (Fig. 1). But, these cells were absent in the follicle-associated epithelium of the ileal Peyer's patches in all the age groups of sheep which is in accordance with Befus et al. (1980) in chicken. When the combined PAS and alcian blue technique was applied, a blue reaction was observed in the follicle-associated epithelium of the ileal Peyer's patches. However, Burns (1982) observed that when the alcian blue was followed by PAS a purple reaction was The follicle-associated epithelium showed positive activity for the alkaline phosphatase. The activity was more intense over the follicle domes (Fig. 2) which is in agreement with Landsverk (1981) in calves, Bjerknes and Cheng (1981) in rat, Burns (1982) in domestic fowl and Owen and Bhalla (1983) in rat. However, Schmedtje (1965) noted that, the lymphoid follicle domes in rabbit appendix revealed negligible alkaline phosphatase activity over the cytoplasmic band separating intraepithelial lymphocytes from the lumen. Nordstrom et al. (1968), Weiser (1973) reported that the alkaline phosphatase activity increased as maturing epithelial cells migrated upto the villi in rats and human foetuses respectively. Ropke et al. (1972) noted in mouse that the high endothelial postcapillary venules through which lymphocytes entered the lymph nodes and Peyer's patches expressed a weak or no reaction for alkaline phosphatase in contrast to other endothelia. Ono (1975) recorded the alkaline phosphatase activity in tubules and vacuoles of enterocytes overlying the follicle in neonatal rats but not in adult animals. Further, Halleraker et al. (1990) observed in ruminant that, the alkaline phosphatase enzyme activity was shown in the follicle capsule. A reticular pattern of staining was found in the centre of the follicle, interfollicular area and in the corona. A weak reaction was seen in the dome. Muscularis mucosae was positive for the enzyme. In lamb, the reticular reaction in the dome of the ileal Peyer's patches was absent. Nicander et al. (1991) reported that in sheep and goat foetuses by 90 days of gestation, a positive band of alkaline phosphatase activity was seen at the base of the villi in the follicular area. Weaker staining was observed in stromal elements of subepithelial tissues in both villi and primordial domes. ii. Acid phosphatase An intense enzyme activity was observed in the follicle associated epithelium and dome areas of ileal Peyer's patches (Fig. 3) which is in accordance with Owen et al. (1986) in rat. Halleraker et al. (1990) stated that the cells stained for acid phosphatase were interpreted as macrophages in the follicle and dome in ruminants. A strong activity in the interfollicular region and a mild activity of the enzyme in the capsule was observed in the ileal Peyer's patches. A pattern of enzyme activity was noticed in the follicles. However, Halleraker et al. (1990) stated that, the smooth muscle cells and reticular cells of the interfollicular tissue reacted strongly. A linear reaction outlined the follicle capsule. iii. Adenosine triphosphatase A linear activity of the enzyme was observed in the capsule of the ileal follicle (Fig. 4). A mild enzyme activity was noticed in the interfollicular region and a weak positive reaction for the enzyme was observed in the follicle. However, Nicander et al. (1991) noticed a stronger activity of enzyme within the follicle and more pronounced activity within the centre of the follicle by 128 days in sheep foetuses. Halleraker et al. (1990) found that in lambs, the reticular cells stained weakly for this enzyme in the T-cell area and in the centre of the follicle. The follicle capsule had a weak, linear and discontinuous staining. iv. 5'nucleotidase A reticular pattern of enzyme activity was observed in the follicles of ileal Peyer's patches (Fig. 5). A linear activity of the enzyme was outlined in the capsule of the follicle which is in accordance with Halleraker et al. (1990) 2012![Global Journals Inc. (US) 11 Global Journal of Medical Research Volume XII Issue VI Version I observed in the epithelium of Peyer's patches of the N. K. B. Raju ? , Geetha Ramesh ? , Sabiha Hayath Basha ? , S. Ushakumary ? & R. Suresh kumar ¥ ear 2012 Y domestic fowl.Lalitha (1991) found that, the PAS positive mast cells were observed in the peripheral (Ovis aries) cortex of the lymphatic nodule of Peyer's patches in buffaloes.](image-2.png "T © 2012") 2![Fig. 2 : Photomicrograph of ileal Peyer's patch of one year-old sheep showing positive alkaline phosphatase activity (arrows) in the domes.](image-3.png "Fig. 2 :") 34![Fig.3 : Photomicrograph of ileal Peyer's patch of five month-old foetus of sheep showing an intense acid phosphatase activity (arrows) in the internodular and a linear activity in the capsule. Lf-Lymphoid follicle](image-4.png "Fig. 3 :Fig. 4 :") 5![Fig.5 : Photomicrograph of ileal Peyer's patch of eighteen month-old sheep showing a pattern of 5'nucleotidase activity (arrows) in the follicles. Lf-Lymphoid follicle Tm-Tunica muscularis 5'nucleotidase x 40](image-5.png "Fig. 5 :") © 2012 Global Journals Inc. (US) © 2012 Global Journals Inc. (US) © 2012 Global Journals Inc. (US) ## Legends To Figures * Theory and Practice of Histological Techniques, 5th Edn JDBancroft MGamble 2003 New York Churchill Livingstone * Gut-associated lymphoid tissue in the chicken ADBefus NJohnston GALeslie JBienenstock J. Immunol 125 6 1980 * A band of alkaline phosphatase activity in the crypts of mouse duodenal epithelium MBjerknes HCheng J. Histochem. Cytochem 29 1981 * Histology and Immunohistology of Peyer's patches in the domestic fowl (Gallus domesticus) RBBurns Res. Vet. Sci 32 1982 * Organization of ruminant Peyer's patches as seen with enzyme histochemical markers of stromal and accessory cells MHalleraker TLandsverk LNicander Vet. Immunol. Immunopathol 26 1990 * Functional studies of Peyer's patches: Evidence for their participation in intestinal immune responses WJurg RAMuller-Schoop Good J. Immunol 114 1975 * The role of Payer's patches in the local immune response of rabbit ileum to live bacteria DFKeren PSHolt HHCollins PGemski SB J. Immunol 120 6 1978 * Gut-associated lymphoid tissue in Indian buffaloes (Bubalus bubalis). Ind PSLalitha Vet. J 68 1991 * The epithelium covering Peyer's patches in young milk fed calves. An ultrastructural and enzyme histochemical investigation TLandsverk Acta Vet. Scand 22 1981 * Immunohistochemical study of the blood and lymphatic vasculature and the innervation of the mouse gut-associated lymphoid tissue BMa RVonWasielewski WLindenmaier KE JDittmar Anat. Histol. Embryol 36 1 2007 * Ontogeny of reticular cells in the ileal Peyer's patch of sheep and goats LNicander MHalleraker TLandsverk Am. J. Anat 191 1991 * The embryology of domestic animals DMNoden ADe Lahunta 1985 Williams and Wilkins 178 Baltimore * Quantitative determination of enzymes in different parts of the villi and crypts of rat small intestine. Comparision of alkaline phosphatase, disaccharidases and peptidases CNordstrom ADahlquist LJosefsson J. Histochem. Cytochem 15 1968 * The fine structure and localization of alkaline phosphatase activity of the small intestinal epithelium in the postnatal developing rat KOno Acta. Histochem 52 1975 * Cytochemical analysis of alkaline phosphatase and esterase activities and lectin binding and anionic sites in rat and mouse Peyer's patch M-cells RLOwen DKBhalla Am. J. Anat 168 1983 * Morphometric and cytochemical analysis of lysosomes in rat Peyer's patch epithelium: their reduction in volume fraction and acid phosphatase content in M cells compared to adjacent enterocytes RLOwen RTApple DKBhalla Anat. Rec 216 1986 * Estimation of the developmental age of ovine foetus and lamb CRichardson CNHebert STerlecki Vet. Rec 99 1976 * Histochemical studies of high endothelial venules of lymph nodes and Peyer's patches in the mouse CRopke OJorgenson MHClaesson Z. Zellforch 131 1972 * Non random distribution of intraepithelial lymphoid cells in follicle associated epithelium of Peyer's patches in mice JRowinski JLamprecht PSicinski J. Anat 131 1 1984 * Some histochemical characteristics of lymphoepithelial cells of the rabbit appendix JFSchmedtje Anat. Rec 151 1965 * Handbook of Histological and Histochemical Techniques UBSingh SSulochana 1996 2 * Premier publishing house Edn Hyderabad * Intestinal epithelial cell surface membrane glycoprotein synthesis: An indicator of cellular differentiation MMWeiser J. Biol. Chem 248 1973