Peculiarities of the morphology of the fish stomach

The stomach of fish provides the first stages of food digestion, as well as adaptation to specific ecosystems and food resources, which is important for the ecology and protection of fish biodiversity. studying the structure of the stomach at the macro- and microscopic level is one of the urgent problems of ichthyomorphology, veterinary and Fisheries practice. However, modern studies on the morphology of the stomach of fish are mainly devoted to pathological changes in infectious and invasive diseases, the impact of adverse environmental factors, conditions of detention, and anthropogenic load. The aim of the work is to conduct a scientific review on the study of the morphology of the stomach of normal fish. Electronic search for publications has been conducted in the web of Science, Scopus, PubMed and Google Scholar databases, mainly over the past 20 years. The principles of objectivity and a comprehensive attitude to the study of the chosen problem are used. The authors of the review article review the current scientific literature and summarize current knowledge on the morphology of the stomach of fish of various classes and species. The anatomical structure of the fish stomach is described taking into account its anatomical areas. The classification of fish stomachs depending on their shape is presented. According to the description of the microscopic structure of the fish stomach, the structural components of its membranes are characterized. The microscopic structure of the surface and glandular epithelium of the mucous membrane is presented, the types of gastric glands and their localization are indicated, and the micromorphology of the layers of the muscle membrane is described. Information from the histochemical study of the stomach of fish of various species is considered. In general, the described anatomical features of the stomach of fish are relevant both for the comparative anatomy of fish of different classes. Data on the microscopic structure of the structural components of the gastric membranes of fish are of practical importance for assessing the morphofunctional state of fish of a certain species and age, which is important for the scientific substantiation of technologies for their cultivation and mastering the mechanisms of development of diseases of the digestive system. Histochemical characteristics of the stomach of fish can serve as a theoretical basis for the development of a normal stomach test system for detecting functional changes under the influence of environmental factors.