The Morphological Structure And The Distribution Of IgA And IgG Antibody Secreting Cells In Pharyngeal Tonsils Of Newborn And Adult Yaks

Pharyngeal tonsil(PhaT)belongs to the mucosa associated lymphoid tissue and plays an important role in mucosal immunity of respiratory tract.IgA and IgG are secreted by IgA and IgG antibody secreting cells(ASCs),respectively,and they have extensive immunological function.In order to study the changes of morphological structure of pharyngeal tonsils during the development of yaks,and the distributive characteristics and changing regularities of IgA and IgG ASCs in the pharyngeal tonsils.In this study,anatomical and histological methods were used to observe and compare the morphological structure characteristics of pharyngeal tonsils between the newborn and adult yaks.The distribution of IgA and IgG ASCs in the pharyngeal tonsils of the newborn and adult yaks was detected by immunohistochemistry.Histological results showed that the epithelium of yak pharyngeal tonsils was divided into the non-reticular epithelium and the reticular epithelium.The lamina propria of yak pharyngeal tonsils was composed of the lymphoid follicles and diffuses lymphoid tissue.Many high endothelial venules and lymphatic vessels were seen in the inter-follicular areas or diffuse lymphoid tissues.In the newborn yaks,there were only a handful of primary lymphoid follicles in the pharyngeal tonsils,but no secondary lymphoid follicles.However,not only primary lymphoid follicles,but also secondary lymphoid follicles were found in the pharyngeal tonsils of the adult yaks.In addition,the statistical analysis showed that the number of the lymphoid follicles of adult yaks were much higher than that of the newborn(P<0.01).The immunohistochemical results showed that,in two age groups,IgA and Ig G ASCs were mainly clustered in the epithelium region(namely the subepithelial region of non-reticular epithelium or the reticular epithelium region),were sparsely distributed in the lymphoid follicles and inter-follicular areas or diffuse lymphoid tissue,and were sporadicly aggregated in between the glands,and the distribution of two ASCs were highest in the subepithelial region of the non-reticular epithelium.In addition,the average number of IgG ASCs was higher than that of IgA ASCs in both two groups.The results indicate that the primary lymphoid follicles of yak pharyngeal tonsils have been formed in the newborn stage;IgA and IgG ASCs play an important immunoprotective effect on the mucosal surface through the epithelium;IgG may be dominate in the immune defense of yak pharyngeal tonsils due to there is a preponderance of IgG ASCs in two age groups.This study provides morphological and immunological information for the mucosal immunity and the pathogenesis of related diseases.