Distribution and Morphology of Ghrelin-Immunopositive Cells in the Spleen of the African Ostrich

OBJECTIVE: To investigate the distribution and morphological characteristics of ghrelin-immunopositive (ghrelin-ip) cells in the African ostrich spleen. STUDY DESIGN: Studies were carried out on 12 5-month-old African ostriches (6 males and 6 females). Immunohistochemistry associated with morphological analysis was used in the present study. Statistical analysis was done using analysis of variance statistics software (SAS Institute, 2000) with Duncan's multiple range test. RESULTS: Ghrelin-ip cells were located throughout the red pulp and white pulp in the African ostrich spleen, but without significant difference in density (p>0.05); none was found in the capsule. Ghrelin-ip cells distributed throughout the white pulp included the periarterial lymphatic sheaths and splenic nodules. What's more, the type of ghrelin-ip cells included lymphocytes, plasma cells, and reticular cells; they were distributed singly or in groups and were ovoid or irregular in shape with cytoplasmic staining. In the red pulp there was a greater number of ghrelin-ip cells in the filtration zone as compared to the ostrich nonfiltration zone (p<0.05). In addition, the ghrelin-ip cells in the red pulp were lymphocytes, macrophages, and plasma cells; moreover, they were distributed mostly in groups and were ovoid or irregular in shape, with cytoplasmic staining. CONCLUSION: The ghrelin-ip cells were located throughout the red pulp and white pulp in the African ostrich spleen. Furthermore, the type of positive cells were lymphocytes, plasma cells, reticular cells, and macrophages. These findings indicated that ghrelin might be involved in immunoregulation of the African ostrich spleen.