Anatomical and histological features of the tonsils create favorable conditions for the persistence of microflora in their lacunae (crypts) in violation of protective and adaptive mechanisms. This is due, in particular, to the fact that in the palatine tonsils there are deep lacunas, the lumens of which always contain detritus from rejected epithelial cells and lymphocytes, as well as microflora, for which this detritus is a favorable nutrient medium. In addition, one part of the crypt openings under physiological conditions is covered with a triangular fold of His, and the other part is narrowed or closed by scar tissue, which develops as a result of chronic inflammation. Under these conditions, the inflammation constantly occurring in the tonsils leads to a change in their micro-architectonics, including the microvasculature bed. Thus, the development and maintenance of chronic inflammation is facilitated by the anatomical and histological features of the tonsils. The aim of this work was a comparative study of the features of the histological structure and microcirculatory blood flow of tonsil biopsies in patients with chronic tonsillitis caused by Streptococcus pyogenes. It has been established that the same form of the disease can be accompanied by various types of structural restructuring of the tonsils, which may have an impact on the clinical manifestations of the disease and is associated with its prognosis. At the same time, it was revealed that the operated patients with low clinical efficacy of antibiotic therapy and preserved sensitivity of the isolated microflora in vitro to antibiotics in the removed tonsils showed a similar pathological picture. In the epithelial layer of the tonsils surface, in addition to areas of epithelial infiltration, areas of its thinning or complete desquamation were very often recorded, less often areas with replacement of the integumentary epithelium with scar tissue. The data obtained make it possible to recommend the study of the morphological structure of removed tonsils to clarify the issues of pathogenesis, features of the clinical course and prognosis of the disease.

The accumulation of T lymphocytes in the thyroid parenchyma in autoimmune hyperthyroidism is strongly restricted and may indicate the primary role of T cells in the development of Graves' disease (GD). However, the mechanisms of lymphocytes invasive activity in thyroid gland, as well as morphological rearrangement of the thyroid parenchyma in GD are still unknown. The aim of the present study was to establish the morphological features of thyroid follicles and the intrathyroidal lymphocyte subsets in GD. The results of the conducted studies showed that the outcome of tissue-specific autoimmunity and long term antithyroid therapy in GD patients is a rearrangement of the thyroid epithelium with histopathologic signs of  Hashimoto's thyroiditis, especially in case of  the disease reccurence. In group of GD disease relapse patients the percentage of CD3⁺CD4⁺CD127^LowCD25^High and B1 memory cells were increased (p<0,001), with a decrease in the content of T-activated and cytotoxic activated T-cells, as well as the population of B1 lymphocytes (p<0,01), in comparison with the level estimated in patients with the newly diagnosed disease. In conclusion, our results indicate that intrathyroidal T cell aggression in phase of autoimmune hyperthyroidism, followed by antithyroid therapy, intrathyroidal accumulation of  antithyroid  drugs with restotaration of  the euthyroid state could be the cause of morphofunctional reactions of  the thyroid  tissue that can make a significant contribution to the immunopathogenesis of the disease.

In recent years, there has been an increase in the number of people with an asymmetry of the maxillofacial region and an uneven position of the teeth. Dental erasing is a lifelong process of loss of hard tissue. The aim of the study was to study the dimensional characteristics of teeth in persons of mature age with different degrees of wear of their hard tissues. The object of the study was 204 men and women aged from 21 to 60 years old with varying degrees of the wear erasing of the hard tissues of the teeth. On control and diagnostic models, the degree of tooth erasing was assessed, the height of the anatomical crown, mesio-distal and vestibulo-lingual diameters of the crowns of the teeth were measured. As a result of the study, it was found that in adults with different degrees of erasing of hard tissues, there is a decrease in the height of the anatomical crown from teeth with I degree of erasing to teeth with III degree of erasing by 12-96%. The mesio-distal diameter increases from teeth with the process of the erasing of the grade I to teeth with of the grade II wear by 2-9% and then decreases in teeth with the erasing of III grade by 6-20%. The vestibulo-lingual diameter decreases as the process of the erasing increases from grade I teeth to grade III teeth by 3-26%. In general, the results of the study indicate differences in the size and shape of teeth with different degrees of the erasing and wear of their hard tissues. According to the results of the study, the width of the crown of the tooth is greater with the II degree of the wearing, and the thickness - with the I degree. The superiority of the mesio-distal dimensions is possibly explained by the fact that the measurement boundaries, due to the loss of hard tissues at the II degree of erasing, pass at the level of the equator of the clinical crown. These results have a priority character and are described for the first time. The erasing of the coronal part occurs simultaneously on the teeth of the upper and lower jaws, the process proceeds asymmetrically, which may be associated with the parafunction of the masticatory muscles.

Diseases of the musculoskeletal system in miners who mine non-ferrous metal ores rank high among diseases with temporary disability. In their blood, oral fluid, hard dental deposits, hair, they have high concentrations of essential and toxic elements contained in ores than in workers of other professions of mining and processing plants. This indicates the entry into the body and accumulation of metals from the industrial aerosol of the working area in the tissues. Osteoporosis in miners is detected much more often and has a correlation with work experience. The aim of the investigation was to study the histological picture and ultrastructure of the bone tissue of experimental animals under prolonged exposure to elements of copper-zinc ore. The experiments were carried out on 36 male rats. Animals of the experimental group received daily intragastrically the suspension of copper-zinc pyrite ore powder in 2% starch solution for three months at the rate of 60 mg/100 g of weight. After 1, 2 and 3 months, the femurs were extracted and the content of Ca, Mg, Fe, Mn, Cr, Sr, Cu, Zn, Pb, Cd, Hg in them was studied by atomic absorption spectrometry and also histologically and by electronic microscopy the changes of the structures of the diaphysis and epiphysis including the morphometric parameters (total area of ​​bone trabeculae, transverse size of bone trabeculae and thickness of the articular cartilage, the number of osteocytes and osteons of the diaphysis in the field of view). It has been established that long-term intoxication with a complex of elements contained in copper-zinc pyrite ore causes disruptions in the ultrastructure and micro-architectonics of the lamellar and cancellous tissue in the tubular bones of experimental animals. The destruction of intracellular organelles of osteocytes is revealed, up to their destruction, resorption and thinning of bone plates, increased resorption with the formation of bone erosion, a decrease in bone formation, which increase with an increase in the duration of intoxication. Thus, prolonged intoxication with a complex of elements contained in copper-zinc pyrite ore, by daily medication of small doses of a suspension of ore powder, causes significant disruption of the ultrastructure and micro-architectonics of lamellar and cancellous tissue in the tubular bones of experimental animals.

The increase in the dynamics of migration processes actualizes the need for the accumulation of diagnostic data on the formation of the skeletal system in individuals of different nationalities and ethnic groups arriving from regions with different climatic conditions. The aim of the study was to study in a comparative aspect the dynamics and timing of the completion of synostosing of the tubular bones of the distal upper limb in children and adolescents in Tajikistan. We studied 259 radiographs of the right hand in children and adolescents of both sexes of Tajik nationality at the age of 6-17 years. The degree of ossification was determined according to the 6-point system proposed by Boris Nikityuk: 0 points - the metaepiphyseal zone is open with a cavity, 1 point - the beginning of synostosis, less than half of the zone is closed, 2 points - the process of synostosis covers from half to 2/3 of the growth zone, 3 points - synostosis takes up almost the entire metaepiphyseal zone, 4 points - synostosis is completed, the area of ​​sclerosed bone is preserved in the form of a light strip on the roentgenogram, 5 points - the zone of sclerosis at the site of the metaepiphyseal line is completely absent. For each age, the mean score for the degree of synostosis was calculated. The process of synostosing in the distal epiphyses of the bones of the forearm was completed in girls at the age of 16, in boys at the age of 17. In girls, the completion of synostosing in the metacarpal bones and phalanges of the fingers of the hand was determined at the age of 16 years, in males a year later. The study made it possible to establish the heterochronism of the ossification process in children and adolescents of different sexes. Tajik girls, on average, are one year ahead of boys in terms of the completion of synostosing of the tubular bones of the hand. The absence of a completed process of synostosing in the phalanges of the fingers of a Tajik girl makes it possible to predict that her age is under 16 years old. The incomplete process of ossification in the phalanges of the hand in males in Tajikistan indicates an age younger than 17 years.

The study of the processes of eye morphogenesis in the fetal period of ontogenesis is relevant from the point of view of understanding the mechanisms of the formation of physiological hyperopia in newborns and myopia in childhood later. The greatest transformations in the human fetus are subject to changes in the cornea and shells of the eyeball in the equator area and in the optic nerve disk area. In general, the eyeball grows and develops most actively in the intermediate fetal period of ontogenesis. However, the details of this process are not well understood. The aim of the study is to characterize the quantitative macro-microscopic anatomy of the shells of the eyeball in a human fetus in the intermediate fetal period of ontogenesis. Macroscopically and microscopically, the anatomy of the orbit and eyeball of the fetus at the age of 14-27 weeks was studied by histo-topography. Three age groups were studied: Group I (14-18 weeks) - 36% of observations, Group II (19-23 weeks) - 38% of observations, Group III (24-27 weeks) - 26% of observations, of which 50% of observations male and 50% female. Histo-topograms made it possible to characterize the morphology of all shells of the eyeball (fibrous, choroid and retina), as well as to trace their course in all its parts. The description of the mid-horizontal and mid-sagittal histo-tomograms, stained according to Van Gieson, is presented and a quantitative characteristic of the thickness of all shells of the eyeball in the equator, the posterior pole of the eye and the cornea is given, sex differences are established and their growth rates are indicated. In the intermediate fetal period of human ontogenesis, the anterior-posterior size of the eyeball changes from 6.91±1.22 mm to 12.25±1.61 mm. At some stages of the entire intermediate fetal period of human ontogenesis, the ratio of the thickness of the shells of the eye is comparable (thickness of the sclera - 51%, of the choroid - 29%, of the retina - 20%). The study of the growth rate of the thickness of the shells of the eyeball revealed its greatest increase in the studied period of ontogenesis in the region of the posterior pole (69.06%).

Analysis of the mechanism of action of cyclosporine A suggests that the local prolonged use of this immunosuppressant in glaucoma surgery may increase the effectiveness of interventions. In order to assess the antiproliferative effect and possible cytotoxicity of cyclosporine A for fibroblasts of the human tenon capsule, which are the main source of scar formation during postoperative wound healing, these cells were cultured in a nutrient medium supplemented with cyclosporine A until concentrations of 0.05-2.00 μg/ml were obtained within 7 days. The control group consisted of the culture of fibroblasts of the tenon capsule of the human eyeball without the addition of drugs. The antiproliferative activity of fibroblasts was assessed by determining the monolayer density, proliferation index, culture doubling time and the number of culture doublings. To assess cytotoxicity, cultures stained with trypan blue, Sudan IV, and hematoxylin were analyzed. The proportion of damaged cells in the cultures was quantified by staining them with a "Live/Dead" set of fluorophores. The nuclear-cytoplasmic ratio was also determined. As a result of the study, it was found that in the phase of logarithmic growth of cultures, the degree of increase in the density of the monolayer was inversely related to the concentration of the drug with Spearman's correlation coefficient equal to 0.9. A strong correlation was also found between the values ​​of the proliferation index, the doubling time of the culture, the number of culture doublings and the concentration of the drug in the nutrient medium. In none of the studied cultures, the proportion of damaged cells did not exceed 5% and was not statistically significantly higher than the values ​​obtained for the control group. Thus, prolonged use of cyclosporine A has a dose-dependent antiproliferative effect on human tenon's capsule fibroblasts within the concentration range of 0.05-2.0 μg/ml without pronounced cytotoxicity.

In laboratory studies of the leukocyte blood count in humans with acute opisthorchiasis, pronounced eosinophilia and neutrophilic leukocytosis are noted, also in an experiment in rodents (Oryctolagus cuniculus), when modeling opisthorchiasis invasion, pseudo-eosinophilic leukocytosis and basophilia are noted, without pronounced eosinophilia. In humans with opisthorchiasis, eosinophilia persists in half of the cases during the transition of the disease to a chronic form, while this phenomenon has not been studied in model experiments. The aim of the study was to determine the quantitative changes in white blood cells in opisthorchiasis in the experiment in the late periods of observation. Modeling of opisthorchiasis was carried out on sexually mature male rabbits at the age of 6 months (n = 16). Infection was carried out once orally, introducing 50 metacercariae to each animal. The metacercariae of Opisthorchis felineus were preliminarily isolated under the control of a light microscope from the muscle tissue of Leuciscus idus fish caught in the Tom River (material from the Department of Ichthyology and Hydrobiology of Tomsk State University, Tomsk). The study was started 3 months after infection in the chronic phase of invasion. Ear capillary blood smears of animals were fixed and stained according to Romanovsky-Giemsa and May-Grunwald. The analysis of the results showed the restoration of normal values ​​of individual indicators, with the exception of the number of eosinophils and basophils and all types of pseudo-eosinophils with an increase in the number of monocytes. In general, the leukocyte formula in the chronic phase of opisthorchiasis in animals was characterized by monocytosis, eosinophilia, basophilia, pseudo-eosinophilic leukocytosis and lymphopenia. The number of eosinophils in the observation group compared with the norm and in the group of animals in the acute phase of opisthorchiasis was 3.96 times higher (p <0.05). With an increase in the period of invasion, the number of lymphocytes in animals returns to normal, but does not reach normal values. It can be assumed that the host organism adapts to chronic invasion, and the blood picture takes on a form close to normal. Thus, in case of opisthorchiasis in rabbits after 3 months, changes in the blood formula are noted that are similar to the human body during the chronization of the process, which makes it possible to consider an experimental model adequate for modeling the chronization of invasion. 

The using in clinical practice of devices for radiofrequency ablation of the atrial myocardium significantly reduced the trauma of the operation and reduced the time of its execution. At the same time, radiofrequency ablation does not violate the integrity of the atrial walls, and the isolation effect is achieved only due to structural damage to the myocardium. The study was carried out on biopsies of the left atrial appendages, resected in patients (n=18) suffering from ischemic heart disease and non-paroxysmal atrial fibrillation. The histological structure of ablation lines formed on the myocardium by two different radiofrequency devices was studied. Bioptats of the left atrial appendages were fixed in a 10% buffered formalin solution, then their fragments were performed in a Microm STP120 histoprocessor, which were embedded in Histo-mix paraffin using the Tissue TekR Tek 5 modular system. Paraffin sections 3–5 µm thick were stained using routine histological methods and embedded in Bio Mount medium. Microscopic examination of the preparations and their photographic recording were carried out on a hardware-software complex Nic-Elements AR 4.12.00 on the basis of a research microscope Nicon 50S with a digital camera Nicon DS-Fi. The formation of ablation lines was carried out by: 1) applying one radio frequency exposure; 2) three radio frequency exposures; 3) application of radiofrequency exposure to a persistent reduction in the time to achieve transmurality. The histological study of the results of exposure to the myocardium of the left ears of the heart was carried out in a double-blind manner. The envelope, which contained data on the method of formation of ablation lines, was opened after receiving the results of the histological examination. As a result of the study, it was found that the priority criterion for the usefulness of the formed ablation lines under radiofrequency exposure to the left atrium in patients with non-valvular fibrillation should be recognized as a persistent decrease in the time to achieve transmurality. Based on this criterion, it is possible to obtain ablation lines with a complete absence of viable cardiomyocytes in their zone.

Male factors of infertility, including a decrease in the quality of sperm, account for 25-60% of cases of infertility in general, of which about 30% of all cases are attributed to the so-called idiopathic infertility. This requires a more detailed study of the morphological and functional characteristics of spermatozoa and their ultrastructural components. The aim of the study was to study the main morphological and functional characteristics of spermatozoa in subfertile men of reproductive age. The material for the study was sperm samples from 85 patients aged 25 to 45 years. The study included 25 clinically healthy men - comparison group; the group of patients who asked for help in order to optimize reproductive health and planning for procreation consisted of 60 men. Routine examinations were performed using a phase contrast microscope. Sperm counts were performed in Makler's chamber. The study of the ultrastructure of the spermatozoa was carried out by the method of electron microscopy. The average values of percentage of progressively motile spermatozoa in the group of subfertile men with reproductive health problems were 33.08±2.1%, which is lower than in patients in the comparison group – 54.35±2.58%. An ultrastructural study of sperm cells in subfertile men revealed fragmentation of sperm DNA. The highest percentage of DNA fragmentation was found in subfertile male smokers and elderly men (more than 22%). In a group of patients with normozoospermia, abnormal acrosome morphology was revealed in samples of spermatozoa with a normal head shape. Acrosome abnormalities are found in more than 50% of men with idiopathic infertility. A study of men with astheno-teratozoospermia and men with idiopathic infertility indicates the presence of large (more than 1/3 of the nucleus area) vacuoles in the chromatin of sperm nuclei with a normal head shape, which reduces the chance of pregnancy. In the group of men with normozoospermia - patients with idiopathic infertility, spermatozoa with a missing postacrosomal sheath were found. Thus, spermatozoa with structural abnormalities are found in varying amounts in the ejaculate of subfertile men, including cases of idiopathic infertility. Subfertility in men can be caused by an increased content of spermatozoa in the ejaculate with certain structural anomalies. The use of electron microscopy in the examination of men with reproductive dysfunctions gives a more complete picture in elucidating the causes of spermatogenesis disorders.

May 13-14, 2021 in Saint-Petersburg, in the Kirov Military Medical Academy the 25th anniversary All-Russian scientific conference «Histogenesis, reactivity and tissue regeneration» took place. The conference was organized by the leadership and staff of the Department of the Histology with of a course of the Embryology of the Kirov Military Medical Academy and by the Scientific Medical Society of Anatomists, Histologists and Embryologists of Russia. This was the first face-to-face meeting of domestic morphologists after long months of the pandemic of the new coronavirus infection COVID-19. The main goal of the scientific forum was to discuss topical problems of histology, embryology and cytology as fundamental sciences and medical teaching disciplines. The conference was attended by about 100 representatives of Russian scientific histological schools - morphologists from different cities of Russia (St. Petersburg, Moscow, Yekaterinburg, Orenburg, Tyumen, Arkhangelsk, Tver, Kazan, Samara, Ufa, Astrakhan, Kaliningrad, Ivanovo, Cheboksary, Vladivostok, Rostov-on-Don, Nizhny Novgorod, Stavropol, Smolensk and others). Among the participants were the heads of the morphological departments of 27 medical universities of the Russian Federation, the Kirov Military Medical Academy was represented by teachers of a number of departments and employees of the research center. The conference participants were not only famous professors-histologists, researchers of morphological departments of research institutes, university teachers, but also young scientists, residents, post-graduate students and students. The conference participants noted the importance of treasuring up of the common research and pedagogical space, of the areas of research in histology, embryology and cytology traditional for the national school of histologists, the development of new forms of scientific research and teaching, which are based on digital technologies. The effectiveness of distance learning among graduate students and teachers of medical universities, taking into account the achievements of digital morphology, is beyond doubt, but at the same time students must also master practical skills in working with a microscope and microscope preparations, which is impossible with distance teaching. The Kirov Military Medical Academy as the organizer of regularly held scientific conferences of histologists, contributes to the treasuring up and development of traditional domestic areas of research, the introduction of scientific achievements in the educational process.