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

Abstract

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

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“…Myofibrils consisted of myofilaments and had characteristic alternating dark and light stripes. As noted in the literature (Khomych et al, 2013), since the light and dark stripes are located at the same level, the muscle fibre looks striated.…”

“…The muscle tissue of squid was white, while mussels were white and pink in colour with different markings. It was formed by smooth muscle cells that had a microscopic structure similar to the smooth muscle tissue cells of aquatic mammals (Khomych et al, 2013). These are fusiform cells with a single, centrally located oval-shaped nucleus.…”

“…These are fusiform cells with a single, centrally located oval-shaped nucleus. Their length was about 100 microns, while in aquatic mammals these cells can reach up to 200 microns (Khomych et al, 2013), and…”

Morphology of the Gastrointestinal Tract and its Lymphoid Tissue in the Common Blackbird (Turdus merula)

“…According to some authors (Kharchenko, 2004;Khomych et al, 2020), lymphocytes in the composition of gland secretions migrate into the esophageal lumen and are involved in the formation of protective mechanisms of the immune system of the digestive organs. The lymphoid nodules in the lamina propria of the esophageal mucosa in the blackbird were not detected.…”

“…There are isolated clusters of lymphoid cells between them, but the lymphoid nodules are not detected (Figure 3b). Some authors report that single lymphoid nodules can be observed in the mucosa of this part of the stomach in waterfowl (Khomych et al, 2021). Between the lamina propria of the mucosa and muscularis, dense fibrous connective tissue, in which fibrocytes are visible, forms a poorly developed submucosa.…”