Morphofunctional Features of Limphoid Tissue of the Stomach in Some Wild Bird Species

The article presents the results of histological studies of topography, microstructure and functional features of the stomach lymphoid tissue in birds. The research was carried out on 12 species of wild birds belonging to 6 orders. Classical methods of histological specimens staining with hematoxylin and eosin, according to Weigert, Van Gieson, and argentum nitrate impregnation according to Kelemen were used when performing the work. It has been confirmed that the birds' stomach has glandular (proventriculus), muscular (ventriculus, gizzard) and pyloric parts, which are not equally expressed in separate species. In all parts of the stomach, lymphoid tissue is represented by local clusters, which in birds of the orders Galliiformes (P. colchicus, B. bonasia, P. crictatus); Anseriformes (B. canadensis); Passeriformes (P. pica, C. cornix); Gruiformes (G. chloropus, F. atra); Ciconiiformes (C. ciconia) and Columbiiformes (C. livia) are located in the tunica mucosa and submucosa, and in B. canadensis, F. atra, G. chloropus also in the tunica muscularis and tunica serosa. In L. lagopus and G. glandarius, lymphoid tissue has been found only in the proventriculus and its intermediate zone. Structural levels of lymphoid tissue (diffuse form, prenodules, primary and secondary lymphoid nodules) are unequally expressed in the birds' stomach. In B. bonasia, B. canadensis, P. pica, C. cornix, C. ciconia, C. livia, only a diffuse form appears in all its parts. This form of lymphoid tissue is registered in the ventriculus of other birds species and proventriculus in L. lagopus and G. glandarius. All levels of the lymphoid tissue structural organization are detected in the proventriculus in P. crictatus, G. chloropus and in the proventriculus and pyloric part of the stomach in P. colchicus and F. atra. The content of lymphoid tissue is different in parts of the birds' stomach. Most of all it is contained in the intermediate zone of the proventriculus and the pyloric part of the stomach. Diffuse form is the most common among the levels of lymphoid tissue structural organization. The research results make it possible to more fully assess the morphofunctional status of wild birds and, accordingly, to find out the state of their immune system