The aim of this work is to study the histological and histochemical structure of the Harderian gland in indigenous pigeons. Samples were obtained from 10 males and 10 females of adult healthy pigeons. Hematoxylin and eosin, Alcian blue (pH 2.5), periodic acid-Schiff and promo phenol blue, stains were used for paraffin section examination. The gland was teardrop like in shape, light brown to pink in color, capsulated with thin connective tissue. It was multilobular compound acinotubular in structure and lined by columnar epithelial cells. Lymphocyte, plasma cells and plasma cells with Russell bodies were present underneath the epithelia of central collecting duct and around the secretory unite. Histochemically; the epithelial cells of both secretory unites and their ducts contained acidic mucins. Russell bodies gave positive reaction with periodic acid Schiff reagent. The present of immunoglobulin was proved in the cytoplasm of plasma cells with Russell body. There were no differences in Harderian gland in both sexes. In conclusion, the Harderian gland of pigeon was histologically and histochemically well developed, and it is immunological effective secondary lymphatic organ, and it had few differences from the gland of other birds.
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