Introduction: The small intestine of albino rats is a transitive canal between the stomach and the cecum that is closely located from each other, reaches a length of one meter, which in comparison ratio to body weight significantly exceeds the corresponding segment in humans. The aim: The paper is aimed at thorough histological study of the wall and structure of albino rats’ small intestine mucosa. Materials and methods: 30 mature albino male rats were involved into the study. The specimens of albino rats’ small intestine, fixed in 10% neutral buffered formalin solution, have been studied. The study was carried out using conventional histological methods for obtaining serial paraffin sections stained with hematoxylin-eosin. Epoxy plastination of individual tissue samples of the small intestine was performed. Subsequently, polished thin sections were made, stained with 1% methylene blue and 1% borax solution. The obtained specimens were studied on the “Konus” light microscope equipped with Sigeta DCM-900 9.0MP digital microphoto attachment with the Biorex 3 software adapted for studies of such type. Results and conclusions: For the first time in the practice of histological study of the epithelial covering of the mucous membrane of the small intestine, attention is drawn to the specific pattern of its organization on the intestinal villi. It has been found that epithelial covering consists of alternating cluster epithelial aggregations separated by fissured depressions. Since no mentioning about them has been found in the publication, these cluster aggregations of enterocytes can be called epithelial buds of the intestinal villi. Consequently, it can be concluded that with the exception of some specific morphological features, the small intestine of albino rats is homologous to human one by its histological structure, which means that it can be used as a model for various experimental studies.

Architecture of the intestinal crypts of the payers' patches of the albino rats' small intestine. Ukrainian Medical Stomatological Academy, Poltava, Ukraine ABSTRACT. Background. In the Peyer's patches, intestinal crypts are topographically differentiated with respect to their lymphoid nodules. Consequently, two types are distinguished. The first type is associated with the lymphoid tissue of the corresponding nodules, and the second one is located outside of them. Objective. To study the features of architecture of the intestinal crypts of the Payer's patches of albino rats' small intestine. Methods. 30 mature albino male rats weighted 200,0±20,0 g were involved into the study. Sections of the small intestine with Peyer's patches were fixed in 10% neutral buffered formalin solution. Subsequently, serial paraffin sections of 4 μm thick (Microm HM 325), stained with hematoxylineosin, were obtained using the conventional histological methods. Another part of the preparations was plasticized in the epoxy. The analysis of the obtained preparations was carried out using the MBS-9 binocular magnifier and "Konus" light microscope equipped with Sigeta DCM-900 9.0MP digital microphotographic attachment, object-micrometer Sigeta X 1 mm/100 Div.x0.01mm. Results. Payer's patches contain two types of the intestinal crypts, discrete by the bundles of smooth muscle fibers. Lymphoid-associated crypts (i.e., intranodular) are actually offshoots of the extranodular crypt network laid at the base of the intestinal villi of the Peyer's patches. Their penetration into the thickness of the lymphoid nodules occurs around their circumference through local splitting of the bundles of smooth muscle fibers, as a result of which they appear i n the thickness of their peripheral regions, corresponding to T-dependent zones. Conclusions. Despite the common origin, these crypts, differing in localization, differ in thickness (the diameter of lymphoid-associated crypts is on the average of 70 μm, while extranodular crypts are 10 μm narrower in the diameter), as well as in the cytological composition and contents of the internal lumen.

Introduction: The stomach and small intestine are important organs of the digestive system and, to date, they are the subject of research by morphologists, endocrinologists, immunologists, gastroenterologists, and other researchers. The aim: The paper is aimed at the study and systematization of the features of angioarchitecture of the albino rats stomach and small intestine. Materials and methods: The study based on the injection of the blood vasculature of abdominal organs of 20 albino male rats with 5% gelatin solution, colored with filtered black ink, was performed. The specimens were subject to photographing from different aspect angles in their original state, and then, after dehydration in alcohols with the transition to pure acetone, they were embedded in the epoxy. Photographing of the obtained specimens was made by a digital camera, as well as a binocular magnifier MBS-9, equipped with a digital photoattachment Sigeta DCM-900 9.0MP. Results and conclusions: The results of injecting of blood vasculature of albino rats’ gastrointestinal tract with ink mass clearly demonstrate the specific difference in the intraorganic angioarchitecture of its different regions, which depends entirely on their functional purpose in the digestive process. In the stomach, the highest concentration of blood microvessels is in its glandular part, which is explained by the increased nutrient needs of the secretory process of the gastric glands, while the mucous membrane of its fundus (pre-stomach) contains a scattered network of exchange microvessels that only promote the process of regeneration of the stratified squamous (partially keratinized) covering epithelium. In the small intestine, the typical principle of the organization of the microvasculature of its mucous membrane is somewhat modified in the duodenum, which is associated with the presence of mucous (Brunner’s) glands in it, as well as in those sites (starting from the duodenum) where the group lymph nodes (Peyer’s patches) are localized.

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Administration of an antibiotic by any route can cause dysbacteriosis, but its risk is the highest when taken orally, since the drug gets directly into the intestine, affecting microflora. After administration of a broad-spectrum antibiotic, Peyer’s patches of the small intestine of albino rats remained unchanged both topographically and in their total amount. But at the same time, their total area is more than doubled, which, according to our data, becomes possible due to the appearance of a new generation of lymphoid nodules in them. The aim of the research was to study the histological characteristics of lymphoid nodules of Peyer’s patches of the small intestine in albino rats after administration of clarithromycin. 30 mature albino male rats weighing 200.0±20.0 g were involved in the experiment. The antibiotic was administered to the rodents as a supplement to food during their two-meals-a-day feeding. Areas of the small intestine with Peyer’s patches have been studied. Serial paraffin sections have been analyzed using the “Konus” light microscope. Morphometric characteristics of the tissue structures were obtained using the Sigeta X 1 mm / 100 Div.x0.01mm stage micrometer. It has been established that after the course of administration of a broad-spectrum antibiotic (clarithromycin) in the small intestine of albino rats, the topography and total number of Peyer’s patches remain unchanged, while their total area increased by more than twice. This hyperplasia of structured lymphoid tissue in the mucous membrane of the small intestine of animals under the influence of the antibacterial drug occurs due to the appearance of new generations of lymphoid nodules in the Peyer’s patches, among which small, medium and large forms are distinguished, similar to the stages of their development. Each of them is distinguished by its morphological features, primarily, the conversion of the lymphoid-associated epithelium. Therefore, the genetically programmed total number of Peyer’s patches in the small intestine of mature albino rats is constant, whereas the number of lymphoid nodules in them is a variable that depends on the state of the intestinal microbiocenosis.