IL-21and Intestinal Mucosal Immunity Of African Ostrich Chicks

African ostrich brood time is90days. During this period, intestinal mucosal immunity system is vulnerable to outside antigens, which would bring huge loss to the ostrich farming industry. Recent studies found that IL-21is closely linked to intestinal mucosal immunity, but the study of IL-21in ostrich intestinal mucosal immunity has not been reported recently. Therefore, Id,45d,90d healthy African ostrich chicks and adult ostriches were studied for the experiment to provide important reference on breeding management, physiology research, disease prevention for ostrich farming. With the methods of dissection techniques, molecular biology techniques, electron microscopy, immunohistochemical techniques, staining techniques and so on, every ostriches gut, brain and other organs were carried on comprehensive study. The results are as follows.1The ultrastructural changes of the intestinal mucosaThe ultrastructural changes of the intestinal mucosa in1d and adult ostriches were studied by transmission electron microscopy.1d ostrich microvillus were arranged neat and orderly. The lamina propria cells were complete. More cells had a lot of mitochondrion in cytoplasm. The absorptive cells were arranged tightly with the nuclear clearly and the cytomembrane completely. The adult ostrich intestinal mucosa microvilli were disorganized. Some cells were incomplete in lamina propria, and absorptive cells had multiple nucleoli phenomenon. It turned out that the intestinal defence function will be improved.2The developmental changes of intestinal plica and myenteric plexusAfrican ostrich gut was observed by HE and PAS. African ostrich has intestinal plica and myenteric nerve plexus are exceedingly rich. Transverse section of Id ostrich intestinal myenteric plexus were round or oval arranged fasciculate. Cells in the myenteric plexus are small and close together. The cross-section of myenteric plexus become longer and cells arranged loosely. So plica can enhance mechanical digestion, rich myenteric plexus make ostrich enteric nervous system function more sensitive.3The developmental changes of intestinal mucosal immune cells at different ages1) The developmental changes of intestinal intraepithelial lymphocytes and goblet cells were studied by HE and PAS staining respectively. Intestinal intraepithelial lymphocytes were small and dark blue. Goblet cells were red and include many granules. The number of epithelial lymphocytes in ileum was the highest. The45d ostriches had the highest epithelial lymphocytes, but in the large intestine90d was the highest. Goblet cells were the most in45d. The results showed intraepithelial lymphocytes and goblet cells play the key role in early development of ostrich intestine.2) The intestinal mast cell were studied by Toluidine blue staining. African ostrich intestinal mast cells with various shapes, mainly located in the lamina propria not in the muscle. The morphology of1d and45d ostrich intestinal mast cells were normal.90d and adult ostrich intestinal mast cells were found the phenomenon of degranulation. The number of intestinal mast cells first increased then reduced from duodenum to rectum to reduce at the same ages. The number of mast cells in the same intestine increased with the ages. The result showed that mast cells in ostrich were almost mucosal mast cells, involved intestinal mucosal immune. It indicated that the system of intestinal mucosal immune is much better after brood period.4The level of IL-21in serumTo research the relation between IL-21in serum and intestinal mucosal immune, the blood were studied by ELISA. During ostrich brood time, the concentration of IL-21in serum showed a gradual upward trend from1d to90d. The concentration of IL-21in adult ostrich serum was the lowest. The results showed that the results will be as the indicator for inflammation diagnosis.5The distribution of IL-21in the African ostrich gut and brain at different agesTo improve the function of IL-21between intestinal mucosal immunity and brain-gut axis, the distribution of IL-21in African ostrich gut and brain were studied by immunohistochemistry. The results showed IL-21in the African ostrich intestine is mainly distributed in the lamina propria, submucosal nerve plexus and myenteric nerve plexus. Lamina propria positive cells were small and round, while the plexus positive cells were large with protuberance. With increasing ages, the location of IL-21positive cells in the lamina propria gradually extends to the enteric cavity. The number of IL-21positive cells in the small intestine was more than in the large intestine. A large number of IL-21positive cells were round, oval and large with no-colored nucleus in the brain. It turned out that IL-21were expressed on T cells and neurons. IL-21is the important factor between intestinal mucosal immune and brain-gut axis.