Manifestation of age-related cognitive impairment is memory decline, the mechanism of which is associated with the activity of the brain as a whole, but the structures of the hippocampus are of particular importance for the process of memorizing current events. Cognitive impairment can be a result of both physiological involutional changes and a sign of neurodegenerative processes. The aim of the study was to evaluate the structural features of the pyramidal neurons of the hippocampus in individuals of different age groups. Using histological, immunohistochemical and morphometric methods, we examined autopsy material (100 samples) obtained from individuals of both sexes of 4 age categories: 22-35 years (n=16), 36-55(60) years (n=30), 56(60)-74 years (n=26) and 75-90 years (n=28). The results of the study showed the presence of dystrophic changes in the hippocampal neurons in individuals of different age categories with a significant predominance of such cells in individuals of the older (elderly and senile) age groups, as evidenced by statistically significantly (p < 0.05) smaller average sizes of neuron bodies in all fields of the hippocampus, compared with similar ones in the group of individuals of the first mature age (p<0.05), as well as in the CA1 and CA3 fields compared with individuals of the second mature age. In mature age, changes in the structure of neurons were mainly reactive in nature. Expressed structural changes of an irreversible nature were observed mainly in the older (elderly and senile) age group. Thus, the conducted study revealed the presence of signs of dystrophic changes in the pyramidal neurons of the hippocampus in individuals of older age groups. With age, the maximum cross-sectional area of ​​all cerebral ventricles increases, the relative volume of vascular plexuses decreases, the relative volume of connective tissue grows, it most likely replaces the cells of the vascular plexuses. The accumulation of Tau protein in the cytoplasm of cells in the CA1 and CA3 fields of the hippocampus in individuals of this age category indirectly indicates the presence of a structural basis for a certain degree of cognitive deficit and a high risk of neurodegenerative pathology.

The potential of Boron-neutron capture therapy is driven by its effectiveness for radio-resistant and other types of tumors that are tough to treat with conventional treatments or if they are not available. In order to improve the effectiveness of therapy, the dose of the substance needs to increase, which raises the question of its effect on conventionally healthy tissues. The study is to evaluate the dynamic changes in myocardium and liver in mice caused by a single injection of L-p-boron-phenylalanine, whether it is a therapeutic or sub-lethal dose. The light-optical and polarization microscopic examination of the myocardium and liver of the male mice of the CD-1 (n=54) line was carried out after the injection of the Boron-containing substance (in doses of 700 and 3000 mg/kg; once intraperitoneal) used in clinical Boron-neutron treatment. Evaluation of structural changes in the myocardium and liver was done 1, 3, and 7 days after injection. Cardiomyocytes are susceptible to lytic and contracture damage caused by high doses of the substance. Moderate blood-fullness was observed throughout the study as evidence of hemodynamic impairments. Mononuclear cells infiltrating the liver for 3 days resulted in mono-cellular necrosis, which persisted until the end of the experiment regardless of the dose. Paracentral hepatocytes have been often dystrophic. Regardless of the dose after 1 or 7 days, the number of bi-nuclear hepatocytes was 14-16% higher than the number of control group animals, while for 3 days there was a reliable transient decrease in the number of bi-nuclear hepatocytes both compared to the control group animals and data in other periods of the experiment. The most significant differences were observed in the animal group with the injection of a lower dose. The obtained data show that the used doses of L-p-boron-phenylalanine with a single injection cause non-specific structural changes of the myocardium and liver of varying severity, characterized by dose and time-dependent effects and require study in later periods after substance injection.

Hirschsprung's disease is a complex surgical disorder that requires histological methods to be verified. This disease is part of the neurocristopathies group, which encompasses colon aganglionosis and other structural disorders, about their treatment and diagnostic tactics are still unresolved. The purpose of the study is to identify morphological changes in the colon wall by using a variety of research methods necessary for diagnosing, surgical correction, and predicting treatment results for Hirschsprung's disease. A prospective analysis of their treatment results was performed on the materials of 119 pediatric patients in this study (91 – boys, 28 – girls). Histochemical, immune-histochemical, and electron microscopic methods were performed on the patients' bioptats colon, along with light microscopy for express biopsy and postoperative material stained with hematoxylin and eosin. Morphological analysis of colon biopsy specimens revealed the presence of degenerative processes in all colon shits, which led to the changes of its structures. Intramural nerve fibers and plexuses throughout the colon were hypoplastic and the complete absence of intramural neurons in the aganglionosis zone is what causes this changes. The findings on the changes in the colon shits close to the aganglionosis zone suggest that the neuromuscular, endocrine, and immune system structures in the intestinal membranes are undergoing primary hypoplased. Secondary degenerative changes also occur in patients with age. Despite successful surgical treatment, functional results associated with intestinal motility in Hirschsprung's disease may not always be satisfactory, as evidenced by changes in the structures of intestinal ganglia. The occurrence of enterocolitis is also explained by these changes, both during and after surgery. Our own results allow us to state that diverse morphological examination methods are necessary for different forms of Hirschsprung's disease and biopsy types.

Electrical impedancemetry analysis of the human body component composition has proven itself to be a widespread and quite effective biophysical method of research. One of the conditions for ensuring comparability of the results obtained by different authors is a complete account of the influence of external factors, including the time of day for conducting the study. The objective of this study is the daily dynamics of the indicators of the component composition of the body of practically healthy individuals. The study involved 42 cadets of the Kirov Military Medical Academy, studying in the first year. The indicators of body component composition were assessed using the Tanita 780 MC fat mass analyzer, which allows calculating the content of fat, muscle, and bone mass in the body, body mass index, metabolic age, basal metabolic rate, index of sarcopenia, physical development rating, and others, in total, 41 indicators were assessed. The component composition of the body was assessed immediately at 6:10 after getting up, at 6:40 after morning physical exercises, including a morning jog of 2 km, at 8:45 after breakfast before the start of classes, at 15:00 after classes before lunch, at 16:20 after lunch before self-study and at 21:30 after dinner before lights out. The conducted factor analysis of the obtained data showed that daily changes in the indicators of the component composition of the body are made up of two rhythms: «physical», including indicators of the muscle component, water, basal metabolism and having morning and evening peaks. The second rhythm is «metabolic», associated with the proportion of the fat component of the body, characterized by minimal daytime values ​​​​reaching a plateau in the evening and night time. The most labile are the changes in the fat component of the body. Asymmetry or specific features of the daily dynamics of the indicators of the component composition of the body of the upper and lower extremities were not revealed. It is shown that the most optimal time for studying the component composition of the body is morning (immediately after waking up) or evening (before going to bed.

It is important to examine structural changes in topographically close organs with varying degrees of resistance because the standard method of treating malignant neoplasms uses radiation and combined therapy. The aim of the work is morphological characteristics and analysis of reactive changes in the small intestinal mucosa, structures of the renal cortex and respiratory part of the lung in the early stages after exposure to X-rays on the 1st, 3rd and 5th days. The object of the study is sexually mature outbred white male mice weighing 18-22 g (n=72). Acute radiation sickness was modeled by exposure to X-rays with an absorbed dose of 7 Gray. The standard method for electron transmission microscopy was applied to histological material before examining it through light microscopy after toluidine blue staining. During the first day after the exposure, lumen expansions and deformations were noted in the capillaries of the renal corpuscles, in the capillaries of the respiratory section of the lung and in the stroma of the villi of the small intestine. The basal part of microvillous epithelial cells in the epithelial lining of the small intestine is highly vacuolarized on the 3rd day, causing disruption of cell contacts. The number of mucosal intestinal cells decreases, compared with the indices in intact mice. Deformation and smoothing of the folding of the mucous membrane continues on the 5th day. On the 5th day, the number of macrophages in the respiratory section of the lung sharply increases against the background of reactive changes in the vessels of the microcirculatory bed. In the nephrons of the kidney, vascular changes were noted first in the capillary network of the renal corpuscle, and then in the capillaries located between the proximal tubules of the nephron. The conducted comprehensive study of organs confirms the general idea of ​​the primacy of dystrophic changes in the vessels of the microcirculatory bed of organs with different radiosensitivity (lung, kidney, small intestine) in the early stages of experimental radiation sickness, along with more specific manifestations of the effects of radiation in the epithelium.

Studying the structure of the mucoperiosteum of the anterior wall of the maxillary sinus is of great clinical importance for otolaryngologists, dentists and maxillofacial surgeons. From clinical practice, it is well known about the frequent trauma of the muperiosteum and its weak regenerative potential, but there is no understanding of the basic mechanisms underlying them. This is explained by the lack of complete information about the structural organization of the periosteum from the side of the maxillary sinus and the presence of connections in the composition between the mucous membrane and the periosteal structure. Purpose of the study: to identify the features of the structural organization and intertissue interactions of the mucoperiosteum of the anterior wall of the maxillary sinus. The study analyzed tissue samples from 10 male patients of the second middle age, 38-56 years old, who underwent surgery to remove foreign bodies from the maxillary sinuses using access through the oral cavity. Fragments of the mucous membrane (Schneider's membrane) were taken from the inner surface of the anterior wall of the maxillary sinus. A histological examination of preparations with hematoxylin and eosin and Van Gieson stains was carried out, and their general morphometry was performed. As a result of the study, it was established that the periosteum of Schneider's membrane lacks the inner layer and blood vessels. It is a thin single bundle of collagen fibers, which in some areas is connected through perpendicular collagen fibers to the lamina propria of the mucous membrane. Based on its location in the bone, functional features, and structural features, the periosteum of the Schneiderian membrane can be regarded as a tissue version of the endosteum. A study of the mucoperiosteum of the anterior wall of the maxillary sinus showed that it consists of a layer of respiratory epithelium and a layer of loose fibrous connective tissue; the boundary of this membrane is a single horizontal plate of a compacted bundle of collagen fibers adjacent to the bone. The presence of sections of cross-links between the lamina propria of the mucous membrane and the horizontal compacted bundle of collagen fibers allows us to consider them a single structural and functional complex.

Currently, boron neutron capture therapy is increasingly used to treat malignant tumors. This method is effective against radioresistant tumors and neoplasms that are poorly amenable to traditional treatment methods, but the issue of increasing its effectiveness remains highly relevant. The aim of the study was to study the structure of subcutaneous xenografts of human glioblastoma U-87 MG after local irradiation with epithermal neutrons and/or against the background of treatment with boron-containing substances - borocaptate and boron phenylalanine. Sixty immunodeficient SCID mice with heterotopic xenografts of human glioblastoma U-87 MG cells were used. It was found that after the therapy in all groups of animals by the 7th day there was a decrease in the tumor mass compared to the control group, by the 14th day this indicator was also slightly lower and only the combined administration of borocaptate and boronophenylalanine followed by irradiation led to a reliable decrease in this indicator by 31% (p<0.01). The volumes of the tumor node by the 7th day were 2 times higher than the initial indicators, by the 14th day the growth of the tumor volume decreased on average by 1.25 times in all the studied groups. The most noticeable morphological changes compared to untreated animals were noted in the group of animals that received both boron preparations followed by irradiation with epithermal neutrons. They had a decrease in the proliferative activity of tumor cells and the number of blood vessels, the foci of necrosis were smaller, as were the tumor nodes in general. The obtained data indicate that the methods of animal treatment used cause therapeutic pathomorphosis, but are not able to completely stop tumor growth. The most pronounced effect obtained in the case of using two drugs in combination with subsequent irradiation with epithermal neutrons indirectly indicates their possible synergistic effect, most likely due to an increase in the total dose of boron in tumor cells.

The number of studies of the vessels of the abdominal aorta and its visceral branches using intravital imaging methods has increased significantly in recent years thanks to multislice computed tomography with contrast, which allows the most accurate determination of the size, anatomical branching options and location of the vessels. However, data from different authors differ significantly. The purpose of the study is to conduct a morphometric assessment and determine the topographic features of the vessels of the abdominal aorta based on retrospective data from multislice computed tomography in groups of adults that differ in both age and sex. The study analyzed archival multislice computed tomography angiograms of 800 men and 175 women. Data on the contingent were divided into 3 age groups, the average age for each group was: group I – 27.3±4.8 years for women and 29.6±4.7 years for men; group II – 50.2±7.1 years for women and 53.6±5.7 years for men; group III – 67.1±5.1 years for women and 66.9±4.8 years for men. Visualization of blood vessels and measurement of arterial diameter were carried out using digital computer programs of the radiologist’s measurement station «Syngo.via». As a result of the study, it was established that the diameters of the celiac trunk, left gastric artery, superior mesenteric artery, the diameter of the superior mesenteric artery at the level of 5 mm distal to the mouth of the ileocolic artery, as well as the diameters of the inferior mesenteric artery, right renal artery and aortic artery mesenteric distance had significant statistical age and sex characteristics. The angle of origin of the superior mesenteric artery had a statistically significant difference depending on sex. The diameter of the aorta increases significantly depending on age; this increase is more typical for men than for women. The data obtained as a result of the study may have reference values ​​in the clinic and complement existing knowledge on the anatomy of the abdominal vascular system.

Breast cancer is a heterogeneous malignant disease with a wide variety of morphology, molecular characteristics and clinical presentation. In the formation of the tumor behavioral phenotype and its response to treatment an important role in the formation of the tumor behavioral phenotype and its response to treatment plays the tumor microenvironment, which makes its assessment critical in choosing therapeutic tactics. However, the practical aspects of using breast cancer microenvironment data are insufficiently studied. The aim of the study is to systematize the morphological and functional characteristics of the main cell types in the breast cancer tumor microenvironment and analyze the possibility practical use of these data. The material was scientific databases, information and library resources for the relevant keywords, the analysis included literature from 2018 to 2023. It is shown that the components of the tumor stroma, both the cellular component and the extracellular matrix, play a special role in carcinogenesis, and this role is not always unambiguous. Analysis of cell polymorphism and tumor microenvironment types should not be limited to research interest only, but should also be an integral part of the histopathological characteristics of a specific clinical case for the possibility of its further practical application. The tumor microenvironment is not just a stroma that feeds the tumor tissue, but also an active participant in carcinogenesis. The breast cancer tumor microenvironment includes cellular and extracellular components, each of which has its own functional and morphological subtypes. Tumor microenvironment cells have functional polymorphism, which creates difficulties on the way to obtaining a complete picture of carcinogenesis and mutual influence in the «tumor cell – microenvironment» system. Analysis of the components of the tumor microenvironment, elucidation of its role and complex mechanisms of cellular interaction of the microenvironment with tumor tissue, including the use of artificial intelligence technologies, can significantly advance knowledge about the mechanisms of breast cancer development for the development of effective technologies for prevention and treatment.

Anniversary article dedicated to the 80^th Anniversary of Doctor of Biological Sciences, Professor of the Department of Medical Biology with Course of Microbiology and Virology of the Ulyanov Chuvash State University Valentina Sergeeva.