MORPHOLOGICAL STATE OF ORGANS IN THE ALIMENTARY CANAL OF THE MUTE SWAN

The paper presents data on the histological structure of the gastrointestinal tract of the Mute swan (Cygnus olor). When studying the architectonics of the stomach of a swan, it was found that the wall of its glandular and muscular sections consists of 3 membranes – mucous, muscular and serous. At the same time, the mucous membrane of the glandular stomach is thick-walled, with a high density of excretory ducts of complex gastric glands per conventional unit of area. It has been established that the muscular plate of the mucous membrane of the wall of the glandular stomach is fragmented and its individual myocytes penetrate between the complex glands, which contributes to a more effective excretion of the secretion of the glands. The mucous membrane also contains a muscular layer, which, in our opinion, is associated with an abundance of secreted hydrochloric acid. This can also explain the presence in this section of the stomach of a well-developed submucosa and a thick-walled muscular membrane. The muscular layer of the mucous membrane and the submucosa are also extended to the muscular section of the stomach in swans. At the same time, the cuticle of the muscular part of the stomach is relatively thin, with superficial striation. In the small intestine, the presence of crypts on the entire surface and a denser arrangement of villi were found. This feature indicates an increased absorption surface of the small intestine and is considered as compensation for its anatomical size. The liver of the swans did not differ significantly in morphology from other representatives of the class Aves. However, in the swans, the boundaries of classical hepatic lobules were not detected in the liver, and two nuclei were often visualized in hepatocytes. Thus, the noted structural features of the digestive canal of the Mute swan are physiologically justified and are associated with the trophic specialization of the represented bird species.